When Ronnie Clifford first went to the psychologist in October 2001, he presented his case as an enormous engineering project. Here are the problems, he said, here are the elements and fractures and stresspoints: now put me back together again. Clifford used the metaphor deliberately, for he was trained as an architect and well-versed in the principles of structural engineering and computerized design. For decades, he had made his living understanding why buildings stand.

The therapist, a specialist in post-traumatic stress syndrome, accepted the engineering project, and the two men went to work, six hours a week. "I was in pieces, just falling apart" Ronnie says in the lilt of his native Ireland. "I was having intense dreams. I couldn't get out of the building. I was there every night, trying to get out of the place. I would jerk myself awake, exhausted, in shock. Weird things were happening. I was seeing the number eleven popping up everywhere - like the towers themselves, the way they rose in the sky like an eleven. Whenever I got in the shower, I would constantly scrub my feet, just scrub and scrub, like there was something dirty down there and I had to get it off."

Ronnie drives his dark-green Jaguar around the historic, gas-lit town of Glen Ridge, the New Jersey neighborhood where he lives and works. It's a rooted place of rambling mansions and shops set in a quilt of woody suburbs seventeen crow-miles from Manhattan. He lives with his wife Bridget, and their daughter, Monica, in a charmingly fusty shingle-style house with hardwood floors, windows warped by time, and a garage that was once a livery stable. The vintage gas lights that grace the streets never turn off.

Ronnie is a solid, fair-skinned man with thinning red hair, thick fingers, and freckled arms. His eyes are blue and warm, and squinch into crowsfeet whenever he laughs or smiles, which is surprisingly often. Because he didn't leave his family farm in Cork and head for America until he was twenty-seven, his accent is strong. He is forty-seven but sounds like a boy when he talks, his voice high-pitched and keen with wonder at life's trick connections. He is attentive to the strange atmospherics that have welled up around 9/11, all the coincidences, real or imagined, and the odd numerology of the day. "Something higher was at work," he suggests. "When I look at all the things that happened to me and my family that day, I realize that you couldn't design an algorithm to put all these events together."

Ronnie, who is a tremendously vivid and empathetic storyteller, wasn't shy about accepting invitations from the media, and he became something of a celebrity in the days after September 11. Eventually, though, the media circuit became too overwhelming for him. He couldn't talk about it anymore. He had to shut off the television and retreat from the world. Everywhere he turned, there it was, an image, a reference, a reminder. Even his friends started to annoy him. The consoling phone calls, the well-meaning e-mails, the sympathy cards—he wanted it all to stop.

Over a salmon pasta at his favorite Italian restaurant in town, where the waiters all know him, he asks me, thoughtfully, almost in a whisper, "Have you ever had anyone close to you die?"

My father, I say. He had a heart attack in his car and smashed into a telephone pole.

"Well," he says. "It would be like if someone said to you, ‘Hey, guess what, your dad died. Your dad died. Your dad died.' Every day, every hour, somebody opens it up in your face. Somewhere along the way, I realized, my God, it's never fricking ending, is it?"

***

That morning, before dawn, Ronnie woke up almost giddy with excitement. There had been a thunderstorm the night before, with major power outages across northern New Jersey, but the storms had swept to the east, leaving everything tingly and cool. Ronnie put on a blue business suit and a yellow silk tie. He'd bought them special for this day. He wanted to look sharp for a business meeting at the World Trade Center Marriott with a Chicago software executive. The stakes were high: If all went well, the meeting would profoundly change Ronnie's business life, creating a brand-new company that would design Web applications for large corporations. Ronnie's little sister, Ruth, whom he always called on for fashion advice, had helped him pick out the suit, and had been especially fond of the yellow tie. "You always want to stand out," she'd told him.

Ronnie kissed Bridgid goodbye, took the commuter train to Hoboken, then, because he realized he had time to spare, and then boarded the ferry. The Hudson air was bracing, and the water caught crescents of the morning light as the sun climbed behind the vivid ramparts of Manhattan. "The city was breathtaking," Clifford says. "Before a meeting, it's always important to feel good, and I felt great."

At around 8:45 Ronnie walked into the lobby of the Marriott, which was connected to the north tower by a revolving door. As he was checking his yellow silk tie in a mirror, he he felt a massive explosion, followed several seconds later by a reverberation, a warping effect that he describes as the "harmonic tolerances of a building that's shaking like a tuning fork."

He peered through the revolving door into the lobby of the north tower. It was filling with haze. People were scurrying to escape what had become an "incredible hurricane of flying debris."

Yet Ronnie remained untouched. It was as though the revolving door were a glass portal to another realm, a world of chaos and soot just inches away. The Marriott lobby was calm, the marble surfaces polished and antiseptic. For a few seconds, the two adjacent worlds did not meet.

Then the revolving door turned with a suctioning sound followed by a sudden burst of hot wind, and in came a mannequin of the future. A woman, naked, dazed, her arms outstretched. She was so badly burned that Ronnie had no idea what race she was or how old she might be. She clawed the air with fingernails turned porcelain white. Her skin was black and glistening red. The zipper of what had once been a sweater had melted into her chest, as if it were the zipper to her own body. Her hair had been singed to a crisp steel wool. With her, in the warm gust of the revolving door, came a pungent odor, the smell of kerosene or paraffin, Ronnie thought.

Then the mannequin became a person, crying for help. Ronnie had little idea what had happened to her, or where exactly she had come from, but he knew that whoever she was, she was his responsibility now.

***

Silvion Ramsundar creaks in his black leather sofa, a television remote clutched in his hand, as the jets from JFK Airport whistle overhead. The relentless background keen of the planes has grown so nerve-wracking that he and his wife, Nimmi, have considered moving from their home, in South Ozone Park, Queens. Silvion fingers the bandaged wound on his left shoulder and says, "I hear them all the time, all the time. I can't stand it. Tools of destruction, that's all I can think about. They remind me."

It's not as though Silvion could ever forget, or that he ever truly wants to. He is a head-on sort of person, and he's made confrontation a part of his recovery. In his living room, nailed to the wall for any visitor to see, is a framed pair of photographs of the trade towers, before and after. In the top picture, the metallic duolith gleams in the sun; in the bottom one, there is a smoky void.

"It's part of my history," he says, in a tone that seems to acknowledge that some people might find the photographs oddly blatant. "I worked there for ten years. Everything that I have in my life happened while I was working there - I bought my first house and my first car, met my wife, had my daughter. Now that the towers are gone, it's like my house burned down."

Silvion will talk about that day, but he refuses to believe that his experience are beyond what his own personal resources can handle. The best way to get back to normal, he feels, is to start acting as though everything is normal. He steers clear of shrinks, of twelve-step trauma sessions, of appearance on Oprah. One might say he's in denial of being in denial.

"I've almost displaced the fact that I was there, as though it happened to somebody else," Silvion tells me. His five-year-old daughter, Mariah, wriggles in his lap, careful not to touch his left side. "That's not to say that it's not going to come flooding back someday. But I know this is what's working for me right now. Being home, thinking about other things, not feeling sorry for myself."

Silvion, a genial man in his early thirties, works for Mizuho Capital Markets, which deals with interest-rate derivatives. Like many denizens of the financial world, he does not succumb easily to melodrama. He speaks in the blunt brogue of the borough of Queens, where he has lived most of his life. But he's a native of Guyana, born of Indian parents who moved to New York City when he was a boy, seeking a better life. His mother is a devout Muslim, his father Hindu. His black hair is cropped short, his skin a deep bronze. A long fresh scar tracks across his jawline.

***

Silvion was standing on the 44th floor of the south tower, in the Sky Lobby Café, waiting in the cashier's line with a Danish and a cup of coffee. He was making small talk with Christine Sasser, a friend from his office. He had heard a thud of some kind and thought someone back in the kitchen had dropped a large stockpot. Outside, the morning sky swelled with paper, a glittering budge of confetti. Silvion watched the cloud floating down and wondered what it was. It looked beautiful against the sharp September blue, a trillion motes dancing in the fair light. He squinted out the window for a moment, then proceeded toward the cashier.

He and Christine rode the escalator up to the lounge on the 45th floor, where televisions were blaring. A news show reported that a small commuter plane had crashed into the north tower, but Silvion couldn't see anything out the window. A voice broke over the intercom and announced: "There is a fire in the North Tower. Firemen are on the scene. Do not worry. The south tower is secure. You may return to your offices."

Silvion and Christine decided to go back up. How much damage could a commuter plane do? At the very least, it seemed like a good idea to reassess the situation from their office, then place a few phone calls and collect their most important belongings.

At approximately 8:50, they pushed the up button for the express elevator. Their office was on the eightieth floor.

Their ascent required two separate elevator rides, the first one to the seventy-eighth, and then a second to eightieth. The doors slid open, and Silvion and Christine walked into their office, only to learn that it had been almost entirely evacuated. Only three security guards and a few of the firm's high-level executives remained. Silvion found Charles, a security guard he'd been friendly with for years.

"Where's everybody?" he asked. "It's just a commuter plane."

"No, no, it's big," Charles answered. "An airliner. Look."

Silvion walked around to the far side of the office and gasped. The steel corduroy skin of the north tower had been torn open. Black smoke tendriled through the building's metal grid. Then they saw a man emerge from the hole. He was standing at the edge, looking down, wide-eyed with fright. Then, the man jumped, and Silvion watched him drop all the way down to the ground. That's when he registered the magnitude of the damage across the way, and he pleaded with Charles, "Are you guys leaving? C'mon, let's get out of here!"

"In a few minutes," said Charles. "We've got to check up on the place."

***

"At a certain point," Will Jimeno says, "your house becomes your prison." Will sits at his dining-room table, net to his gun rack, gazing at a deer in his backyard. Ever since he got out of the hospital, in late November, he has sat here - a cop under a kind of house arrest. The view never changes. The TV drones. The deer doesn't move.

In fact, the deer isn't real. It's a target that Will keeps for bow-hunting practice. It's startlingly lifelike, though, a creature comically out of place next to the suburban detritus on the porch. Ordinarily, Will would spend much of the fall in a deer stand in the pine barrens of New Jersey, slathered in camo-scent. But this year he missed the season entirely. For three months he lay in a hospital, his veins coursing with blood thinner. "Next year," he says. "Maybe next year."

Will lives in Clifton, New Jersey, in a modest boxy house clad in green vinyl siding. As we talk, his wife, Allison, bathes their newborn in the kitchen sink, while their older daughter, Bianca, watched SpongeBob SquarePAnts in the other room. Will is a burly man with a round face and black hair cut in a military buzz. He was born in Colombia, but moved to America when he was two and grew up in nearby Hackensack. Before he became a cop for the Port Authority of New York & New Jersey, Will served four years as a gunner's mate in the Navy, pulling several deployments in the Pacific on a ship that carried attack helicopters.

Because of the extreme trauma of Will's injuries, his left leg is bound in a formidable-looking brace, and various crutches and walkers are strewn about the house. He wears a PAPD T-shirt, black gym shorts, and a pair of hospital-issue circulation hose. "Aren't those lovely?" he says. "They come in two different colors - black and nude." Today, it's nude. The hose are pulled up nearly to his knees and push firmly against the skin to prevent swelling.

Will has occasional bouts of depression and despair, but by and large he's optimistic. He's had to keep busy, and that's been a godsend. His days have been taken up with a regimen of treadmills, flexes, weights, hydrotherapy, and stretches. Despite skin grafts and extensive reconstruction to repair the damage to his nerves and muscles, his leg is still a mess. "I'll wear a brace the rest of my life," Will says. "But I will walk again."

In Will Jimeno I see an iron determination to put the best face on things, and a certain resignation, the look of someone young who has begun to accept the indignities of his condition while feeling stabs of incredulity that this is the new him. If there was once a macho aspect to his personality - proud hunter, sailor, cop - it has been humbled.

The proportions of the tragedy still tax his imagination. The Port Authority lost more police office that day than any American police force has ever lost in a single day. Thirty-seven PAPD officers died, along with thirty-eight other Port Authority employees. Many of them were his dear friends. Will says, "I don't think I've internalized it, and I'm not sure I ever will."

He motions for me to come closer, turns his left knee outward, and shows me the leg. "It's getting better," he assures me. His knee is swollen, and the thigh is a swirl of ruptured blood vessels. The skin along his leg is cross-hatched with scars. In his thigh there is an orifice left by the surgical removal of flesh, a ropy-skinned hole that's large enough to accept a cork. "For draining," is all he says, and I don't press him further.

***

Will was working outside the Port Authority Bus Terminal that morning, a rookie cop policing the rush-hour crowds with his Mace and his 9mm Smith & Wesson, when he saw the shadow of a low-flying plane pass over Forty-second Street. A few minutes later, he received an alarm over his radio - a plane had hit the World Trade Center. Immediately, he and nine others boarded a Port Authority bus and sped toward the tip of Manhattan.

When the bus pulled up in front of the towers, everything was coated in a fine gray powder and strewn with chunks of metal and concrete. The carcasses of cars and buses smoldered along Vesey Street. The torched husk of an airplane part was stuck like a harpoon in the side of a building. People lay on the sidewalk, bloody, with paramedics at their sides. Even on the ground, Will could smell the jet fuel. From his years in the Navy, he was well acquainted with its sharp stench, and he something about how hot it burned.

Senior officers were looking up at the fire with tears in their eyes. Most of the Port Authority policemen had suspected this was a terrorist attack right from the start. Ever since the 1993 WTC bombing, the Port Authority had been an agency steeped in paranoia. The World Trade Center was expressly theirs to protect, and they were trained to be suspicious. "As soon as we pulled up to the site, we knew that this was a combat situation," Will says. "Only we were police officers - we were never trained for war."

While fussing with his his equipment, Will kept hearing explosions, one every few seconds, a ragged beat of concussions thudding up and down the street. He turned to look: They were human bodies, dropping from above, blowing up on impact. They sent up aerosol clouds of blood and left divots in the sidewalk. The ground became littered with body parts and personal effects - watches, high-heeled shoes, PDAs, a briefcase. "I've heard experts say the people were dead before they hit the ground," Will says. " But you could tell they were conscious. They saw what was coming."

***

With no medical training, Ronnie Clifford scarcely knew what to do. He sat her down on the cool marble floor, then dashed into the bathroom and ran water into a clean black garbage bag that he found. He hurried back out and dribbled the contents over her body.

Then he sat down on the puddled floor and tried to comfort her. Despite her condition, she was lucid. He took out a pen and notepad from his leather bag and jotted down her information. Her name was Jennieann Maffeo. She was an Italian-American woman from Brooklyn, single, forty years old. She worked for UBS PaineWebber. She was an asthmatic, she said, and had an extreme intolerance to latex. She could not adequately describe what had happened to her. She was standing next to a man she knew outside the north tower, waiting for a bus, when she heard a loud crash above. In an effort to protect them from falling debris, a security guard herded everyone inside the tower's lobby. Suddenly, she told Ronnie, something bright and hot enveloped her, a vapor maybe. She thought it could have dropped down the elevator shaft. She was worried about the man who'd been next to her. Surely he was dead, she feared.

Periodically Ronnie yelled for a paramedic, but no one came. People were streaming through the revolving doors now and scattering. Ronnie didn't know what to do, what to say. His new suit was soaking wet, and wisps of skin clung to it. He sat close to Jennieann, but didn't think he should hold her, for he feared that the germs on his hands would cause a fatal infection. He thought about his headstrong sister, Ruth, and wondered how she would handle this situation. She had once run a European day spa in Boston and had made skin health her professional and personal concern. She knew what vitamins to take, what salves to daub on burns, and she always coached Ronnie to take care of his skin. She would have known what to do.

Jennieann turned to Ronnie and looked beseechingly at him through her half-closed eyelids. "Sacred heart of Jesus, pray for us," she said.

Sitting in a pool of water, alone in the swirling stampede, he whispered the Lord's Prayer in her ear.

***

Anxiously, Silvion and Christine rode the elevator back down to seventy-eight. More than a hundred people were there waiting for express cars, tapping their feet, cutting nervous jokes. They lingered for what seemed like a long time but was probably only a few minutes. Christine tried to make a call from her cell phone but couldn't get a carrier. "This elevator better come soon or else we'll have to take the stairs," Silvion said.

A few seconds later, at 9:06 a.m., Ramsundar glimpsed a brilliant flash of milky light out of the corner of his left eye. The entire wall to his immediate left ripped open, and a pressure wave hurled him ten feet across the lobby. As he tumbled through the air, he felt debris piercing his body. He landed on his back. His briefcase was tossed in the opposite direction. A miscellany of tiles and sheetrock landed on him. He could smell what he later learned was jet fuel, and there were fires all around.

Silvion wasn't sure if he could move. He had cuts everywhere. He was bleeding from his ears, and had a long laceration across his jaw, with the skin hanging loosely from his chin. He was having trouble breathing. Something hard and sharp was embedded in his upper chest, and the wound was pulsing dark blood, a red coin growing on his chest. His left arm dangled lifelessly.

He lay dazed for a few moments, with no idea what had happened. The only thing he could imagine was that an explosion from the other tower had somehow carried over. He studied his wound long enough to ascertain that whatever had entered his body was significant, about the size of a deck of cards. He could neither lift his arm nor move his shoulder. Nerves and muscles had evidently been severed. He worried that the projectile had struck a major artery.

Then he realized that a person was lying across his legs. He sat up and struggled to roll him off. When he saw the man's face, Silvion knew he was dead.

***

Will Jimeno raised his hand to volunteer when Sergeant John McLoughlin, a Port Authority veteran who knew every rivet of the building, asked for men to accompany him into the north tower and start rescuing victims. The group quickly assembled. The four mean were preparing to venture into the tower when the second crash came, the United Airlines jet. Because of the spped and angle of the impact, this second explosion was much more massive than the first. The shockwave working its way down the building, like a thrum in a bell. Even so, Will and his three comrades gathered their equipments and pressed into the World Trade Center.

***

Ronnie Clifford was still whispering the Lord's Prayer in Jennieann Maffeo's ear when the second plane hit. The whole edifice rumbled and groaned and swayed, then the floor beneath him buckled hideously and seemed to raise him off his feet. Pieces of the building were falling all around him. Ronnie knew then that they absolutely must get out.

"Jennieann," he said. "Can you stand up?"

"I'll try," she answered.

Ronnie removed his new suit coat and draped it over her front so that she wouldn't have to walk out of the building naked. A nurse who worked for the Marriott arrived with a bottle of oxygen and a mask, which she held over Maffeo's mouth as they shambled across the hotel's crowded lobby. Drawing closer to the door, Ronnie heard someone say, "A plane hit the tower," and then someone else say, "A second plane hit the other tower," which was the first time he had an inkling of what had happened. He was growing more frustrated and alarmed. The crowds weren't moving fast enough through the bottleneck at the door. Jennieann was in excruciating pain. Finally, Ronnie held her arm and pushed impatiently through the throng.

"Out of our way!" he screamed in a voice he did not know he had. "Make way!" When people turned to look, they shrank in horror, and suddenly Ronnie and Jennieann were able to file straight out the door, as though the waters were parting before them. "It was like I was taking Frankenstein out of the building," Ronnie says.

When they emerged out on the street, Ronnie looked up and saw a lady plummeting toward the ground, clutching her purse. "I keep thinking about that purse," he says. "I can't get the image out of my head. Why was she worried about her purse?"

Even in her state, Jennieann was self-conscious about her nakedness. Ronnie understood that his suitcoat wasn't enough. Then, out of nowhere, a huge gentleman appeared with a clean white tablecloth and gently wrapped it around Jennieann, like a shroud. It was as though he had foreseen her predicament. The man smiled and helped Ronnie get her down the steps.

A fireman was standing on the streetcorner , grimacing at the burning buildings, which were breaking apart. Ronnie could hear the sound of them cooking, the sound of rivets popping, glass shattering under pressure, the sighs steel girders make when they bend. With wild gesticulations, the fireman screamed at the lingering crowds, "Run, run! I'm telling you, just run."

"Can you run Jennieann?" Ronnie asked.

"I think so," she said. She looked at her feet. The rubber soles of what had once been her running shoes were melted to her feet.

"Let's try, then," Ronnie said. He took her arm, and in a tentative, shuffling gait, they ran.

***

On the seventy-eighth floor of the south tower - or, rather, what had formerly been the seventy-eight floor but was now an upheaval of fuel-splattered wreckage - Silvion Ramsundar tried to shake of the shock. The heat was intense, and flames were engulfing the mangled corridors. Is it over? he thought. Am I going to die right here? What happened just now? He peered through the thickening smoke and realized that the majority of the hundred or so people who had been waiting for the elevator were now dead. At least they weren't moving.

Silvion scanned the lobby for his friend Christine and spotted her some thirty feet away, stunned and injured but still alive. She had lacerations on her arms and face, and her left ankle was bleeding profusely. Silvion managed to stand. Picking his way among the bodies, he hobbled over to Christine. She slowly registered his presence. She saw the red stain blooming on his white shirt and said, alarmed, "You're bleeding bad."

"I think I can move," he said. "How about you?"

Christine nodded and struggled to her feet. Silvion remembered that there was a stairwell somewhere near the elevator bank. It was the only way out. They fumbled along the wall, blind, until Silvion grabbed what felt like a handle with his right hand. He gave it a jerk, but it wouldn't turn.

Now the black smoke was so dense along the ceiling that they had to creep on the floor. Not far from the first door, they found another. Silvion gave it a try, and this time the latch turned. The heavy firedoor swayed open - it was the emergency stairwell he'd been looking for. The buckled stairway was hot but relatively clear of smoke. Ramsundar brightened for a moment, then hesitated. He wasn't sure he could make seventy-eight floors. His breathing was shallow and labored, and he was growing weak.

For a brief moment, Silvion gazed back through the smoke. He heard choking, coughing, the cries of the injured. Seventy-five bodies, perhaps more, lay in a tangle on the fumy floor. He thought about his friend Charles, the security guard, and realized he must be dead.

Silvion turned back toward the stairs. He leaned against Christine, and they began walking down in the sodium glare of the emergency lights, on steps that were brightly marked with fluorescent tape. They settled into a pace that was comfortable for him, stopping occasionally so that he could catch his breath. More people filled the stairwell. Some were hyperventilating and removing clothing in response to the heat. Occasionally Silvion had to step around people who could go no further.

Somewhere in the high sixties, they reached a landing that was obstructed by a massive beam. Two large men managed to shift it just enough so that the file of evacuees could crawl through, then resume their descent.

As they walked, people could plainly see that Silvion was critically injured. One man applied his handkerchief to the wound as a compress. Later, a woman removed her slip and cinched it around Silvion's shoulder to stanch the blood. They kept walking.

Silvion kept his mind fixed on the numbers - sixty-two, sixty-one, sixty, fifty-nine - and tried as best he could not to consider his wound.

***

Will Jimeno had spent only nine months on the job as a cop, and although he had undergone an intensive six-month training course at the police academy, he was thoroughly unprepared for the situation in which he now found himself. He had spent most of his brief career on duty at the Port Authority Bus Terminal, a vast and shabby complex in midtown Manhattan. Up until this moment, his most challenging situations had been a shooting incident involving an emotionally disturbed person and the case of homeless man with advanced AIDS who perished on a bus.

Now, the officers were down in the concourse, not far from the Gap, at a point almost equidistant from the two towers and just beneath the famous bronze globe, a sculpture designed to symbolize world peace through world trade. The concourse level was ordinarily a bustling shopping mall, but now it was desolate, and the tile floors ran cold with water from the firefighters' hoses.

The men opened an equipment closet and rummaged from gear: flashlights, crowbars, gloves, first-aid kits, and self-contained breathing apparatuses known as Scott Air-Paks. Their radios, tuned to Port Authority frequencies, blew a constant gale of staticky screams.

Among the group of cops, now numbering five, were a veteran named Christopher Amoroso and two other rookies, Dominick Pezzulo and Antonio Rodrigues. Pezzulo and Rodrigues were close buddies of Will's from his police-academy class. Thirty-six years old, Pezzulo was a funny Italian from the Bronx, a weightlifter who, Will says, was "built like Jean-Claude Van Damme." He had a beautiful wife and two kids, and loved to fish for blues in Long Island Sound. Rodrigues, who everyone called A-Rod, was a colorful bald guy with a thick Portuguese accent. A gifted artist, Rodrigues was always doing caricature sketches of the other cops.

The younger men never questioned Sergeant McLoughlin's judgment. A highly decorated veteran of the department, he had won a medal for his valor in the evacuation following thw 1993 Trade Center bombing. Will says, "If he asked me tomorrow, I'd follow him into that building again."

The five men tossed the paraphernalia into a canvas cart and hustled toward the north tower.

***

Running from the buildings, Ronnie Clifford and Jennieann Maffeo found an ambulance beside a green knoll across West Street, near the World Financial Center. He spirited her, still wrapped in a Marriott table linen, into the hands of the paramedics and gave them the notes he'd scribbled that described her vital facts. Then the ambulance took off for the Weill Cornell Burn Center, uptown.

Ronnie called Bridgid, his wife, from a pay phone. "I'm all right," he told her in a voice that she would later describe as "close to panic." There was a long pause. "I've just gone through something terrible," he said. "I'm alive. I'm ok. I love you."

Ronnie hung up and tried to get his bearings. He turned to look again at the towers. The infernos were raging even more fiercely than before. People were still occasionally leaping from above, while firemen were marshaling in large numbers and marching into the buildings.

He tried to call his sister, Ruth, in Connecticut, but couldn't get through. Ruth lived in an old mansion beside a lighthouse on Long Island Sound. But then Ronnie remembered that she wouldn't be home. She was on a trip to Los Angeles to take her four-year-old daughter, Juliana, to Disneyland and to attend a seminar led by the New Age self-help author, Deepak Chopra. Her best friend, Paige Farley-Hackel, was coming along. Ronnie was sure they were in California by now. Whatever Ruth was doing, he hoped to God she wasn't watching CNN.

Ronnie wasn't sure what to do next. He felt he ought to help people evacuate the building, or volunteer at a hospital. Then he thought about Monica, his daughter. He remembered that it was her birthday and that they'd planned to have a celebratory dinner that night.

She was turning eleven.

***

Dusted in gray flour, Silvion Ramsundar and his friend Christine shuffled out of the south tower around 9:50 A.M. Christine needed stitches for multiple lacerations, but the paramedics were gravely concerned about Silvion's condition. They went to work on him immediately. His left lung had collapsed, his pulse was faint, he'd lost a dangerous amount of blood, he was dehydrated, and he was in shock. A photographer for the New York Post snapped his picture, a portrait that would become one of the more arresting images of the day. His wound had become unbearable. "My body sort of relaxed," Silvion says. "I had a sense of relief - ok, I made it, seventy-eight floors. And that's when the pain really kicked in."

It was only when Silvion was hurtling toward Saint Vincent's hospital in an ambulance that he learned what had happened. "A second plane?" His mind reeled at the implications. The plane had struck the very floor where he had been standing; the gas he'd smelled was jet fuel. It couldn't have been an accident. He was having trouble absorbing this. But by then, the morphine had begun to take over.

***

Reversing his course from earlier that morning, Ronnie Clifford boarded the ferry to Hoboken. The ferry operators weren't even bothering with tickets; they were simply ushering people aboard. During the ride across the Hudson, Ronnie stood at the stern of the boat and watched the buildings burn. His begrimed jacket was slung over his shoulder, a sordid memento of a business meeting that was not to be.

Then, at 9:59, just as he reached the creosote piers of New Jersey, the south tower collapsed. In a terrific, thunderous implosion, the eleven became a one.

***

The Port Authority officers were directly beneath it all. Within seconds, Will Jimeno and his four partners were assaulted by concrete, tile, marble, and a hail of glass shards. There was a tremendous snarling roar, which Will could feel more than hear. Sergeant McLoughlin pointed toward a safe place, behind a massive concrete pillar. As they dashed toward it, the tower came down on them. Will momentarily lost track of everyone else. He ran until the world became dark and close and his body could no longer move.

He couldn't catch his breath. He couldn't see. It felt as though someone had poured hot sand down his through. His who left side and his right foot were pinned down by something large, as if the weight of the tower was bearing down on him. He was coated in a puree of insulation, Sheetrock, fabrics, fibers, papers, paints, plastics, wiring - all the substances of society, the mingled grounds of the modern would. It got in his ears, his lungs, his mouth. Even now, six months later, Will can smell it. He calls it "the smell of the World Trade Center."

Finally, the cloud began to dissipate, and tiny shaft of light slanted in. Will couldn't see the sky, but there was just enough filtered light for him to make out shapes. He was in what amounted to a tiny cave, trapped by a piece of an elevator shaft. Various fires flicked in pocked and folds all about him. His radio was out of reach.

Will called for Pezzulo. "Dom, you all right?"

"Yeah, I'm here." Pezzulo was also pinned. He lay only a few feet away from Will. Once the dust settled a little more, they could see each other.

They heard McLoughlin somewhere in a void below. The sergeant was gasping in pain, trapped in the fetal position. H couldn't see a thing, nor could the other men see him. By the sound of things, the sergeant was in worse shape than Will. "Somebody relieve the pressure!" McLoughlin yelled. "I can't stand it."

"A-Rod? Chris?" Will called out for the two other, but he got no response.

Then they were assailed by a horrible chirping sound, incessant and shrill, like a dozen car alarms going off. It was the Air-Paks, strapped to the men's backs. An Air-Pak has an attached motion detector; if its wearer doesn't move within one minute, an alarm is triggered. The signal is incredible harsh and loud so that rescuers can located a fallen or trapped comrade. But now so many Air-Paks were sounding off all around the World Trade Center that there was little hope of locating any one. The alarms were canceling each other out by their sheer numbers. It sounded like a field of crickets.

***

Ronnie Clifford took the commuter train home from Hoboken. Next to him sat a lady who was deep into a bottle of booze. The cars were overcrowded with people on cellphones balling to their spouses. Someone nearby had a Blackberry, a wireless internet device, and was receiving chilling updates on the tiny screen. Another one's hit the Pentagon. Another one's gone down in Pennsylvania. Another one's heading for the White House.

As the train hummed and clacked west toward home, Ronnie's thoughts drifted back to Jennieann. His heart went out to her. It seemed she had saved his life, just as he had saved hers. If he had remained in that building much longer, perhaps helping other people, he'd be buried now. If the horrified crowds in the lobby hadn't instantly made way for them, he might still be trapped. In the queer way fate had worked, Jennieann had been his ticket out. He prayed for her.

***

Just minutes after the south tower fell on Will Jimeno, his buddy Dom Pezzulo managed to free himself from the rubble. Pezzulo thought about crawling toward the hole to seek help, but decided to try to extricate his friends instead. It soon became apparent that the cause was hopeless, but he clawed at the debris with his bare hands for about a half-hour, struggling with blocks of concrete ten times his size. The Air-Paks shrieked relentlessly.

Then Will heard heard another noise, another rumble in the distance, like the wrath of a volcano. Pezzulo backed up a few feet and braced himself for another collapse. "Oh, my God," Will said. "Here we go again." The north tower came down around them. It was 10:28.

From above, a jagged block of concrete fell through the hole and tumbled into their crawl space. Will watched as the slab struck Pezzulo and "laid him down like a rag doll." Pezzulo withered in pain. He made a wisecrack to the sergeant, something about requesting permission to take a coffee break. He was losing a lot blood. He turned and said, "I love you, Will."

Will said, "I love you, buddy."

"Don't forget," Pezzulo added. "Don't forget I died trying to save you guys."

Then Pezzulo unholstered his 9mm sidearm, pointed it up toward the hole, and fired off a single round. "It was like a last ditch effort," Will says, "as if to say, We're down here, come find us."

Will watched as Pezzulo slumped back and gasped for air. His gun fell to his side.

John McLoughlin, unable to see anything down in his black hole, shouted through the pain, "What's going on up there?"

"Sarge - it's Dom. He's gone. I just saw him pass."

***

A team of plastic surgeons at Saint Vincent's sutured Silvion Ramsundar's chin back together. Then they went to work on his chest. His shoulder blade was broken, and the piece of shrapnel was lodged dangerously close to his aorta. The doctors worried that if they weren't extremely careful in removing the object, they could paralyze his arm for life. One they dug out the gobbet with their surgical tools and examined it, the doctors decided it was a shard of metal from the airplane that crashed into his floor. Silvion wanted to keep it - a piece of that day once embedded in his body - but later an FBI agent arrived with Ziploc bag, marked it EVIDENCE, and carried the artifact away.

***

When Ronnie Clifford arrived home in the late morning, he embraced Bridget, and then climbed upstairs straightaway for a shower. More than anything else, he wanted to rinse off the residue of his morning. At least he had his daughter's birthday party to look forward to. He paused to think about what his would mean for Monica as she grew up, to have turned eleven on September 11th, 2001. Monica was across the street at school - innocent, for now, of what had transpired in the city.

Ronnie, it turned out, was innocent, too. He had assumed it was only fair, after witnessing so much, after doing his part as a good Samaritan, that he should sail away on the Hoboken ferry, unscathed. But then he received a piece of news by phone from his brother-in-law that, with a bit of work on the internet, he confirmed. Among the ticketed passengers on American Airlines Flight 11, the first plane, the one that hit the north tower, had been Paige Farley-Hackel, his sister Ruth's best friend, and a close friend of his. A little later in the afternoon he was able to verify an even more devastating fact: Ruth and her four-year-old daughter, Juliana, had been on the second plane, the United Airlines flight from Boston.

Ronnie had somehow lost track of when Ruth and Juliana were supposed to fly to Los Angeles. He thought they'd gone out the day before. Paige had intended to fly with Ruth, but there'd been some kind of mix-up at Logan. Paige took American, Ruth took United, but they both ended up in the hands of hijackers, friends in separate missiles aimed at the same target.

Ronnie tried to imagine Ruth's last moments on the plane. Most likely, Ronnie thought, she would have been sitting calmly in her seat as they banked low over the Hudson. And in the seconds before the plane hit, she would have been holding little Juliana, and singing a song in her ear.

***

Will Jimeno and Sergeant McLoughlin were the only ones left. Amoroso, Rodriguez, and now Pezzulo were all dead. The two men waited for hours for something to happen. Occasionally fireballs floated down into the hole and landed beside them and then extinguished themselves in the wreckage. One of them must have landed near Pezzulo's Smith & Wesson and heated it up. The gun went off, and bullets ricocheted around the hole. "You're not going to believe this, we're getting shot at!" Will yelled to McLoughlin.

They talked to each other a lot during the afternoon, the veteran sergeant and the rookie. They talked about their families, about life and death, about their buddies who lay buried about them. Both men were in agony, squirming under the pressure, their arms and legs swelling. But they were lucid. With his free hand, Will tried to chip away at the concrete with his handcuffs and spare magazine of his gun. It was useless. Every couple of minutes he would yell out, PAPD 813!" which is Port Authority code for officer down. But as midday stretched into late afternoon his calls began to lack enthusiasm.

Then, from the hole above, Will heard a voice. Someone was frantically shouting a name, then, "Are you down there? Are you down there?"

Will couldn't catch the name, but he shouted back—"Sergeant McLaughlin and Officer Jimeno are here!" He was ecstatic. But then the voice left and never returned.

Will began to talk to himself out loud, a stream of dire thoughts. He thought about Allison, his wife, who was seven months pregrant. "At that point I pretty much accepted death," he says. "I asked God to watch over Allison and my little four-year-old and the new baby girl. I wanted to see the baby, just once."

At around 8:00, Will was aroused by another voice. "United States Marine Corps, can anybody hear me?"

Will yelled back, "Don't leave us! The last guy left us."

Then a marine trained his flashlight into the hole and spotted him. "I'm not leaving you," he said.

Soon the paramedics came, and firemen and cops and Port Authority officers, a long trail of men harnessed to one another, clambering over the pile. For three hours they dug and scraped and sawed, pulling away the rebar, widening the hole. They used bare hands, welding torches, buzz saws, the Jaws of Life. Finally, they reached Will. They feared they would have to amputate his left leg, but at last budged the pillar just enough to slip him free.

They would get to McGlaughlin, but first they slide Will into a basket and hauled him out. It was 11:00 at night, thirteen hours after the south tower had collapsed. Will looked around at the devastated site, a smoky panorama of harsh lights and humming generators and flickering welders' sparks.

"Where is everything?" he asked.

One of the officers leaned over and said to him, "There's nothing left, kid. It's all gone."

***

Later in September, Ronnie Clifford went to visit Jennieann at the hospital. She was wrapped in gauze from head to toe, save for narrow slits for her eyes and her mouth. Although Jennieann was heavily sedated and could not talk, her sister said she was aware of visitors. Ronnie sat with her for awhile, and urged her to be strong. Before he left, he placed his yellow silk tie on the pillow beside her, the tie he'd been wearing on the eleventh, the one Ruth had coached him to wear. Ronnie wasn't sure why this gesture had occurred to him. He just wanted for her to have something to remember him by. Something that stood out.

Jennieann was in the hospital for forty-one days, drifting in and out of consciousness. The mounting infections, the skin grafts, the side effects of her medications - it was all too much for her system. On October 21, she died of kidney failure.

The same day, workers at Ground Zero located Ruth's remains. The family had already held a service for her and Julia a month earlier. More than twelve hundred people showed up. There had been long bittersweet remembrances and a Celtic bagpiper. Ronnie organized a huge party afterward on Ruth's front lawn.

As soon as he got home from the funeral, Ronnie collapsed in exhaustion. "My emotions were swimming around," he says. He was a nervous wreck. One time Monica and a friend were horsing around on the hardwood floor and made a sharp thumping sound. Ronnie completely lost it. All he could think of was falling bodies, the woman with her purse. He couldn't get the images out of his head.

Finally recognizing that the problem was "far greater than anything I could deal with," Ron went to a psychologist's office. Doug, the therapist, sat back in his reclining chair and invited him to talk about his life. He asked Ronnie to keep a journal of his dreams. He put him under mild hypnosis and had him relive every sight and smell and sensation of that horrible day. What started out as six hours a week has since fallen away to one hour every other week. The engineering metaphor has proved apt.

***

Mostly, Silvion Ramsundar misses the views. The way electrical storms scudded out to the Atlantic, the sunsets that went on forever, the morning sun lighting up the clustered spires of lower Manhattan, the Statue of Liberty standing sentinel at his feet.

Silvion spent two weeks mending in the hospital, followed by months of physical therapy to restore his shoulder. The arm still tingles and throbs, and it bothers him in countless little ways. As he talks, he twists and flexes his arm. "They say it's never going to be 100 percent," he says. "It gets all locked up. I can't pick Mariah up the way I used to, to take her to bed. But they say, just be grateful you can use your arm at all."

When he arrived home from the hospital, Silvion didn't relive the incident, exactly, but he had bad dreams: He kept finding himself trapped in a fire, smashing up his car, being chased. Then he started having anxiety attacks whenever he drove over a bridge. In daydreams and reveries, Silvion can still summon the sight of the Sky Lobby with sickening vividness. That he survived the blast through nothing more than dumb luck, an accident of position, troubles him. "There was only one quadrant on that floor that was safe from the plane, and it happened to be where I was standing," he tells me, with fresh amazement. "If I'd been standing ten feet to my left, maybe I wouldn't be sitting here. Had I been a foot to my right, maybe the debris would have hit my heart. Why me? Why not the guy standing next to me. How come I was in the right place?"

In the past few months, Silvion has logged some serious quality time with his family. Chores around the house, countless trips to Home Depot. For ten years, he lived at the speed of Wall Street. These days, he doesn't bother getting up until nine. Sometime in the spring, Silvion plans to return to work at Mizuho Capital Markets and get back in the derivatives game. In a very real sense, Silvion has been Americanized, secularized, confirmed in the high church of pluralism and the mutual fund - the very things, of course, that make the terrorists burn. And yet one of the odd twists to the whole event, for him, is that because he is of Indian descent, dark-skinned and raven-haired, he sometimes gets the look, the double take of suspicion. Who are you, where are you from, what's hidden in your shoes? "It's justifiable," he reasons. "Until this threat is completely gone. I have to expect it."

As he talks, he sits beneath his before-and-after diptych of the trade towers and assures me, with a kind of provisional confidence, that he's okay. He has one modest request, though. If he has a choice, he prefers not to work in a high-rise. "I'm good on the ground floor," he says.

***

Will Jimeno has no idea where the rumor started, the beautiful, fantastic rumor. In the hours after they were discovered in the rubble, he and Sergeant McLoughlin became the subject of an incredible story repeated so often that the national media reported it as confirmed fact: A Port Authority cop, in some accounts several, was said to have "ridden the wave" of debris down from the eightieth floor and survived with barely a scratch. It was the kind of legend that springs up in the chaos of a catastrophe - a wildly untrue story that reflects true hope. All around the world, people were praying that more victims would be pulled alive from the ruins. If a man could ride down that mighty wave and live, then there was still a chance.

When he got to Bellevue Hospital, Will was assaulted by a green army of surgeons. He didn't understand why, with a tragedy of such mammoth proportions, he should get such solicitous treatment. He didn't understand that, at that point, there were no other survivors. He was the survivor - he and his sergeant and a handful of others. The green army rolled him into the operating room and set to work. He had a condition known as compartment syndrome. The wracking pressure in his leg had built up so powerfully that when the doctors cut it open that night, blood and backed-up fluids sprayed the walls like a Jackson Pollock canvas.

In twelve days, Will had eight operations to excise the dead tissue and relieve pressure. The doctors worried about blood clots and kidney failure and gangrene. When they suctioned out his upper airway, the vacuum ticked and chattered with the sound of grit. At one point, Will saw a rock sliding up through the tube.

All those weeks in the hospital, Will though about his comrades day and night. He still does - especially Pezzulo and Rodrigues. He can't get them out of his head. He's commiserated with their wives, described their bravery. Sergeant McLoughlin, who was pulled out of the rubble eight hours after Will, was released from the hospital in January, after kidney dialysis and some two dozen operations, He's improving gradually. "One day at a time," Will says. "Like me, he's trying to get by."

Will has decided to remain with the PAPD, maybe working at the pistol range. "I have moments where I'm not happy, where there's mental anguish," he says. "But right now I'm at peace with this. I didn't live through all this just to quit."

Before 9/11, Will and Allison knew there were having a baby girl, but they had bickered over the name. Will wanted Alyssa. His wife wanted Olivia. When they found him in the rubble that night, he asked someone to call Allison and tell her to name the baby Olivia. "If I didn't make it," he says, "I didn't want her to feel guilty about going with the name she wanted."

Now Will is holding his newborn, a beautiful three-month-old with a full head of hair. She was born November 26, which is also Will's birthday. He was there at the hospital at Allison's side, crying in his wheelchair. Now he lifters her up and holds her high over his head and smiles up into her eyes. She smiles back.

Her name is Olivia.

***

The first time he went out after September 11, it was as though he'd never been on the water before. He's been a sailor ever since he was a boy in Cork, and in recent years he's kept a 26-foot fiberglass boat in a slip in the Bronx. Now, though, was unsteady, indecisive, skittish. He was reluctant to heel her over in strong winds. He was nervous about every little piece of the rigging. Whenever the boat made a shudder, his heart raced. At what seemed like his lowest moment ever, he found himself looking across Long Island Sound, struggling to comprehend the gap in the skyline.

But Ronnie kept at it. Every weekend, he was out there on the Sound. As the fall progressed the winds grew stronger and he began taking more risks. One day he was out in twenty-five-knot winds and he realized something extraordinary was happening. He was smiling.

Even the hole in the skyline ceased to prey on him as it had before. He scarcely even noticed it.

Sitting in the library of his house in Glen Ridge, I ask Ronnie if he thinks he'll ever find meaning in September 11th - the day his daughter turned eleven, the day his sister and niece smashed into a building at the very moment he was reciting the Lord's Prayer into the ear of a horribly burned stranger. "Meaning?" he says, turning the word over in his mind. "It was so horrible, so horrid, so horrendous, there's got to be goodness afterward. To me, the Trade Towers represented positive and negative. Before and after. Good and evil. Two ones."

Outside, in the broad daylight, I can see the vintage gas lamps burning up and down the street.

"For me," Ronnie says, "the meaning is the rest of my life."