As convincing in drag as he is surrounded by zombies, Cillian Murphy can have any kind of career he wants, but he's determined not to get caught up in "the nonsense of the film world."

Cillian Murphy scurries into the third-floor bar of London's Century Club—the social establishment where he scored a free temporary membership by virtue of his starring role in John Kolvenbach's play Love Song.

His oddly enormous blue eyes peer out from between a tangle of tousled hair and a face full of scruffy beard. "I must say that I apologize," he says, slumping into a leather armchair without bothering to remove his coat. "I'm tired. I went to Dublin yesterday to do a read-through for Brendan Gleeson for a script that he's doing. It's called At Swim-Two-Birds, [based on] a really famous Irish novel. It was me, Colin [Farrell], Gabriel Byrne, Brendan, and those other Irish actors. And I ended up staying out all night. I won't fall asleep, I promise."

When he mentions that he also played a little music last night, revisiting those pre-acting days when he was in a band and turned down a record contract, his Dublin jaunt starts sounding like a very glamorous way to get hung over. But Murphy is quick to diffuse any notion that this was anything other than a typical night at the pub. "Was I serenading Colin? Is that what you're asking?" He jokes. "No, he went home. He was a good boy. No we were just—a guitar came out and we were playing. You know, Irish people do that."

With major roles in films like Red Eye and Batman Begins, Murphy has thrived in Hollywood. But he lives in London and remains rooted in the classically European attitude of working to live rather than the reverse. The 30-year-old husband and father—who is married to his sweetheart of more than a decade and took eight months off when his son, Malachy, was born in 2005—calls acting "the best job in the world, because it allows you to work for a limited amount of time during the year, and you can then live off that and just do other things. I mean, it is my passion, and I want to improve at it as best I can. But I don't in any way want it to take over my life. That's why L.A. can be very tiresome, because it's just a nonstop roller coaster of fucking actors and directors."

This is not to say that Murphy doesn't enjoy the occasional loop-de-loop—but only when accompanied by a talented director in passion of a good script. He's been in 14 films, playing wildly various roles ranging from Scarecrow in Christopher Nolan's Batman Begins to one of the last survivors unaffected by a rage-inducing virus in Danny Boyle's 28 Days Later… to a sugary transvestite named Kitten in Neil Jordan's Breakfast on Pluto, for which he earned a Golden Globe nomination. "If any film doesn't have aspirations to be a piece of art," he says, "then I'm not really interested in doing it."

The two latest projects to meet Murphy's rigorous standards will hit screens this spring: The Wind That Shakes the Barley, Ken Loach's 1920s-set drama about two brothers torn asunder by the Irish civil war, and Sunshine, a space thriller that reteams Murphy with Boyle. Although Sunshine is "a rollocking good adventure," says Murphy, "there are arguments and themes that are fundamental. For me, ultimately, Sunshine is about science versus religion, and about if the sun does die, should we interfere with God's will to keep it going or should we let it die? I'm an atheist, but I find that with this whole thing of intelligent design and everything we've got going on that it's an argument that's quite current and relevant."

During the rehearsal period, Boyle asked his cast to live together for two weeks in a tiny East London studio reminiscent of the cramped quarters of a spaceship. "I think we found out who were the good cooks and who weren't particularly," Murphy says. "I'm vegetarian, so I cook veggie stuff. I just think meat is so full of shit now that there's no point." He also experienced zero gravity, trained in a flight simulator, read astronauts' accounts of going into space, and hung out with Geneva physicists experimenting with a particle accelerator.

The Wind That Shakes the Barley, winner of Cannes' Golden Palm last year, brought Murphy down to earth, specifically where he was raised. "I was living in my parents' house where I grew up in Cork," he says. "My wife was pregnant with my boy, and it was just a really lovely time. I was doing a film where I didn't have an accent, and I didn't have to change myself. It was just me." He plays a doctor-turned-freedom fighter, a neat fit for an actor who has "a good bedside manner," according to Loach. "Ken shoots chronologically, and the actors aren't given the script," Murphy continues. "He sometimes will shoot a scene and not look at you; he'll just listen. So it's a very private experience. It's as far removed from the whole nonsense of it as you can get. And in an ideal world, I think all films should be shot like this."

Of course, there are pitfalls to living so organically inside a fiction. While Murphy doesn't stay in character between takes, he admits that there's a certain "residue" from playing extreme roles like Pluto's Kitten. "My wife will tell me, 'during this period, you were fucking crazy.' I don't generally party, but there was a lot involved in that one. That's [Kitten's] world, you know." And his Red Eye costar Rachel McAdams says he was equally in tune with the hostage-taking assassin he played in that Wes Craven thriller. "He always had this knife with him. It was a prop knife, but he would be throwing it around. He's a drummer, so I think he's a very tactile person, and that was a way to keep his machine well-oiled. And it was great intimidation for me. I was like, 'Perfect. I love that. I encourage you to explore that more, Cillian'."

On this particular evening, Murphy is laying off the cutlery. In fact, the wiry actor has barely moved since he collapsed in the chair; his limbs seem to be conserving energy for the play he'll perform in two hours' time. "To me, it's a very delicate thing, acting," he says, downing a cappuccino. "It's not very different from just being, you know? I think that once an actor becomes a personality, there's a problem. I don't want the audience to have any preconceptions."

Does this mean he's envisioning a character actor's career? "I guess so," he says, then flashes a subversive grin. "But I want to play the leading roles!"