Not surprisingly, bears are an unavoidable fact of life for the family that chooses to inhabit the forest with more beasts per square mile than any other place on Earth — a.k.a Bear Island. All season long, the bear populations have been a secondary character to the Brown family, and as time winds down before they head into hibernation, the grizzlies and black bears of Chichagof Island have grown more ravenous by the week; but it's not until the family returns from last episode's fishing trip to find their cabin absolutely torn apart, despite their best efforts to bear-proof it in their stead, that they confront the issue.
The cabin is disheveled to say the least — there is feces on the living room floor, the foundational pillars of the house have claw marks ripped through them, and the protective two-by-fours covering the windows have been completely snapped. But it's an all-too-familiar scene for the Brown's, and when Matt inspects the perimeter to learn more of the bear's habits, he doesn't have to go far before actually discovering the culprit — a massive young male black bear who's totally unafraid.
It's time to act, so the Brown's toss around some ideas to scare the bears away, from using the foghorn from the boat to lighting flares. Quirky Rain has the coolest idea — "What we really need to do is find a baby bear and raise it, and then we have our own bear that's on our side." But, of course, it's going to be the tinkerer, Noah, who will act as the real brains of the operation. He jumps in the little skiff and sets off for the trash dump in nearby Hoonah, where he searches for any salvageable parts to build a "bear alarm."
Noah discovers the red-and-blue sirens from the top of an old cop car, and creates a circuit board out of random junk like a video game controller and a butter knife, in order to wire the siren, lights, and a motion sensor together — creating one hell of an alarm. It almost makes you wonder what he could be capable of had he been given the chance at a real education.
In the meantime, the rest of the family is working on something just as cool as Noah's scavenged creation — a 150-square-foot tree house high above the forest floor. The brothers use pulley systems to hoist massive floorboards into the air and end up building a sweet shelter the family can escape to at a moments notice.
But it won't be needed, when the bear returns at night, Noah's bear alarm goes off without a hitch, sending the beast back into the forest. With the bears seemingly at bay, the older Brown boys turn their focus to what will be a central part of next week's season finale — a new hauling job, twice as far as their last trip to Gustavus, which didn't exactly go over well. It's a chance to earn the family some money, but also a shot at redemption in their father's eyes; but as they set sail at the close of the episode, storm clouds roll in and the waves begin to whitecap. tree houses and bear alarms won't be of any use to them here.