Liev Schreiber is describing the ghastliest scene you will never see in the new Second World War movie Defiance. “It’s called a Bielski enema,” says the 41-year-old actor (pronounced Lee-Ev), who stars opposite Daniel Craig and Jamie Bell as the real-life Bielski brothers, leaders of a unique and often ruthless Jewish resistance who operated from the dense woods of Belarus. “It was one of the things the brothers did when they’d catch Germans, to make an example of them. They’d insert potato-masher grenades in their rectums and just let them explode.”

This particular torture, mercifully, never made it into the finished movie, but was part of the brutal historical detail that drew Schreiber, an accomplished stage actor who made his name in the Scream franchise, to the role (“I started to understand what these guys had to become to achieve what they did”). He was also drawn, he says, by the chance to investigate his own heritage (his mother is Jewish, of Ukrainian and German descent), and to tell a story that turns the traditional Holocaust logic of Jewish victimhood on its head.

And yet, ironically, the greatest revelation in Defiance is not the justified historical revisionism but simply Schreiber himself. Normally the go-to guy for angstridden urban intellectuals (see his introverted novelist in The Daytrippers, or passive senator in Jonathan Demme’s Manchurian Candidate remake) here he straps on a submachinegun and a bowie knife and makes the recalcitrant middle brother, Zus Bielski, into a fiery, trigger-happy avenger, part Rambo, part Lee Marvin. “It’s funny, because Ed [Zwick, the director] was saying that to me a lot, when we were making it,” he says. “He’d be like, ‘We are really redefining you right now!’ ”

Meanwhile, Schreiber’s next role is even more action-packed — he stars as the mutant supervillain Sabretooth opposite Hugh Jackman’s Wolverine in the comic blockbuster X-Men Origins this summer. The role, which required four months of bulking up and working out (transforming his already imposing 6ft 3in frame into a thing of hulking beauty), is the final step in Schreiber’s transformation from a man who’s all brains into one with muscles too.

“I like to think I’m part of the new Obama transition,” he says, tongue deeply in cheek. “Obama is hermetically intelligent, he knows what he wants and he never screws up. So maybe now there’s room for intelligent action heroes too.”

The real kick here is the sheer breadth of Schreiber’s professional evolution. A Tony award-winning stage dynamo, he has repeatedly wowed New York critics and crowds alike with his headlining Shakespearean roles (from Cymbeline to Hamlet to Henry V and beyond) since graduating from Yale School of Drama in 1992. “I do think there is some truth to the notion that you have little to fear from any role if you can comfortably break down a Shakespearean soliloquy,” he says, without false modesty.

His acting, he says, has complicated roots and comes from a childhood that is infamously dysfunctional. A simple précis couldn’t possibly capture the texture of it (the essayist and writer John Lahr tried to do just this in a lengthy New Yorker magazine profile of Schreiber in 1999). The key points include an early divorce between Schreiber’s blueblood father Tell and his Jewish former communist mother Heather; some time in an upstate New York commune with Heather; Tell kidnapping Schreiber back from Heather; a custody battle won by Heather, followed by a childhood for Schreiber dominated by his mother’s penury (they frequently had no electricity, hot water, or even beds).

He endured her mood swings and bohemian proclivities (she made him take Hindu names, wear yoga shirts, and he was forced, briefly, to go to an Ashram school in Connecticut when he was 12). It culminated in a fractured ankle during football practice at Brooklyn Tech in 1984, when the 17-year-old Schreiber was forced to turn away from sports and eventually towards the stage.

Acting, says Schreiber, is therapy. “I may have been working out my relationship with my mother and my father all along, and I probably will be for the rest of my life. But then that’s one of the luxuries of being an actor — it’s about self-exploration.”

He is now based in Manhattan and in a long-term relationship with fellow actor Naomi Watts, and his life at the moment is defined by the couple’s two infant children, Sasha, 17 months, and four-week-old Samuel Kai. “Remember that voyage of selfexploration I was talking so fondly about just then?” he says, chuckling to himself. “Well it just ends. You go, ‘Awhh s***! No more me time!’” He then sighs and quietly confesses: “I am struggling, though. It’s f***ing hard. So little sleep. It’s 23 hours and 59 minutes of exhaustion. But then they do one little thing in that last minute that is just so compelling and fascinating that it makes the other 23 hours and 59 minutes worthwhile.”

Furthermore, he adds, children give you some much needed perspective on your work. Because despite the fact that he has a summer blockbuster on the way, and a romantic comedy with Helen Hunt called Every Day, plus a Jude Law sci-fi film, Repossession Mambo, he is still wildly unsure of his career prospects. “You can never be comfortable as an actor,” he says. “It’s like Heisenberg’s Uncertainty Principle. The minute you name an event it ceases to exist. It’s like that with acting. The minute you say you’re happy with your career, it’s gone. Over.”

Defiance is released tomorrow

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