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In 2001, David Benioff—whose novel The 25th Hour would soon be turned into a movie—made a few nice Hollywood deals and (ho hum) also signed a three-book package with Viking. Now, after writing the scripts for Troy, X-Men Origins: Wolverine, The Kite Runner, et cetera, he has finally delivered another novel: City of Thieves, a gripping, at times gory, but ultimately sweet story about two young men sent on a suicidal mission to find a dozen eggs during the siege of Leningrad. It has the phenomenal twists of, yes, a great movie—one of which had us fooled. He clarified matters for Boris Kachka.

So in your preface, you explain that this is based on your grandfather’s own amazing story. When did you start interviewing him for it?

All four of my grandparents were born in the United States and died here, and it’s really pure fiction.

Really? Well, I’m a little embarrassed.

I don’t think it’s embarrassing. A lot of people have asked me about my grandfather. But I thought that’s what it meant when you put “novel” on the front. The truth is, out in L.A., people would ask what I do and I’d say I’m a writer, and they’d say, “Movies or TV?” And I’d say, “No, I just wrote a novel,” and they’d say, “Fiction or nonfiction?” So maybe it’s not as clear as I thought.

It’s a great hook, your “grandfather,” but isn’t it a bit misleading?

[My publishers] said, “You can be really coy about it, just don’t lie.” But I want to be up-front about it. I sent an e-mail to my editor when the James Frey scandal broke, saying, “I promise I’m never going to send you anything that’s not a complete work of fiction.”

Did your publisher know it would take you five years to hand over a novel?

I kept lying to them, basically, saying “I’ll have it for you in a year and a half.” I was really worried that I’d spent too much time away from it and that I was done as a novelist.

It is a little cinematic. It even has kind of a happy ending.

Well, I don’t want to give anything away, but do you think it’s a happy ending? A really bad example of this would be the second Die Hard movie, where ten minutes before the end, this planeload of innocent passengers crashes and hundreds of people are killed, but because Bruce Willis defeats the bad guys and gets the girl, we’re supposed to think it’s a happy ending. It’s pretty far from a happy ending.

So have you sold it as a movie yet?

No. If a great director came along who wanted to do it, I’d be interested. I’d have a very hard time saying no to Peter Weir. But I’m not interested in selling it to a studio. I like having my own story remain my story.

And yet you have no problem adapting everything from Homer to Khaled Hosseini into blockbusters.

But I like blockbusters. I love Wolverine—I aggressively pursued that.

What are you working on now?

I’m doing a series at HBO. A crappy way of describing it would be The Sopranos in Middle Earth. I was a huge fantasy geek growing up. I was the dungeon master in my D&D game. Actually, most writers I know were the dungeon masters.

City of Thieves.

Viking. 272 pages. $24.95.