You imply that 'City of Thieves' is your grandfather's story filtered through his grandson's novelistic imagination. Is that true?
I can only say, without revealing more than I want to, that this is a work of fiction. If you bill something as a memoir, you're implying that everything in it is true.

That's a refreshing viewpoint these days, considering all the false memoir scandals.
I wrote to my agent after the James Frey thing exploded: "I promise I'm never going to send you anything that isn't a lie."

Do you need to maintain two separate brains for writing screenplays and for writing fiction?
With screenplays it's all about being as concise as possible. If you have a scene that's set in a bar, you just have to write, "INTERIOR: BAR." This was the first fiction I'd written in seven years, and I'd developed some lazy habits.

Is that why it's proven so elusive for writers to be successful as both screenwriters and novelists?
Most good novelists writing plot-driven stuff can do it. Dave Eggers has a new screenplay that I hear is amazing. But novelists are used to being the kings of their domain, whereas many screenwriters succeed because they take direction well.

Your first screenplay was the adaptation of 'The 25th Hour,' your first novel. Did you have any screenwriting ambition before that?
I never considered it until I moved to L.A., where you tell people you're a writer and they ask, "TV or movies?" If you say, "Novels," they say, "Fiction or nonfiction?"

Your wife [Amanda Peet] once joked in an interview that she only married you so that you would write a great role for her. Are you working on that?
She said that? Well, I did figure out a story for her that I hope to direct. It's the least commercial idea I've had yet, and if I were a studio exec hearing it I think I'd chase me out of the room. Hopefully she'll accept the role. It'd be pretty embarrassing if she turned it down, wouldn't it?