"As a Jew, I thought, I don't want to fuck around with this subject," he says. "Holocaust movies are upsetting to work on. The genre scares me. An action movie about 'fighting Jews' could feel Hollywoody."

Shooting in Eastern Europe would mean three months of cold weather and crap food. He fretted that nobody would buy him as Daniel Craig's brother—performers from different countries wouldn't sound believable as Lithuanian-accented siblings without months of prep. "I just thought, Oh, man, what a mess."

Zwick sat there patiently, Schreiber recalls, "and said, 'Oh, it's interesting that you think that.' He absorbed all my negativity—and didn't address any of it! And he was right. Those were my anxieties to sort out." Schreiber was in. He went off to learn Russian.

"Liev is scary smart, and he loves that Talmudic, dialogical give-and-take," Zwick says. "But you know, when you're trying to load a gun and your fingers are frozen, you don't need to talk about Stanislavski a lot. The hardest thing [for Schreiber] is the abundance of choices—he could do it any number of ways and they'd all be good. But how are you going to do it when there's only one take because we've rigged an explosion?"

Schreiber figured it out, giving an unsentimental, brutally credible performance that sparked an Oscar campaign. From Bielski in Defiance he moved on to Wolverine, then did a turn as a gender-bending Korean War vet in Ang Lee's sixties comedy Taking Woodstock, and is now in production on the indie domestic drama Every Day, in which he stars opposite Helen Hunt. It's an odd path for a guy who says that the "emotionally bruising" experience of directing an adaptation of his friend Jonathan Safran Foer's Everything Is Illuminated a few years ago left him feeling that there were more fulfilling ways to spend his time than working on movies. "But for people who may feel alienated, acting is a way to connect to your own humanity, and an escape," he says. "It's like your friend coming over and saying 'Come on, shake it off. We're going for a bike ride right now. Enough of your bullshit.' And you go, and you feel better."

Schreiber is itching to get back onstage. He and Watts are the parents of a toddler, Alexander, who was born in the summer of 2007, and a new baby, Samuel, born in December. Film work leaves him with "a really bad feeling about moving around a lot," he says. "For a child, there's something to be said for the underpinnings of home. Theater gives you a really good daddy schedule—you hang out with them all day, put them to bed, and then go to work. And even then, all you have to do is fail. That's what theater rehearsal is: 'Leap, fail, try again. Leap, fail, try again.'" In movies, he says, "it's just 'Leap.'"