What could be more refreshing on a hot summer day than a gruesome thriller set in a snowy Siberian wasteland? Horror fans may think they're on a well-worn track when Transsiberian premieres this Friday in New York. Thanks to its claustrophobic journey by train and morally ambiguous heroine, the movie world seems determined to compare it to Hitchcock's classics, but star Emily Mortimer believes the film isn't so easily classified.

"It starts off as a Hitchcock movie, but it becomes more of a Dostoevsky novel in the end," says Mortimer. "The morality of Hitchcock films is often questionable, but that's not the theme of this film. Hitchcock's films are sort of chillier... and that's what I like about them. But Transsiberian is an investigation of guilt, and whether you really can get away with murder in your own mind, whether you can keep that secret and carry on with life -- which is more in line with Dostoevsky." Director Brad Anderson (The Machinist) is inclined to agree.

Mortimer plays Jessie, a woman whose seemingly wholesome married life is a mask concealing demons from her sordid past -- and the actress was able to draw from plenty of real-life experience. "My dad is a criminal defense lawyer. He defended a lot of murderers, and he would always say that they were generally the nicest clients he had," she explains. "And it's a crime that he thinks anyone could commit -- whereas not everyone could hold up a bank. Most of us have it in us to kill someone at some point in our lives, and my dad brought me up with an open-mindedness and respect for that fact."

Her observation of the criminal mind hasn't been entirely second-hand, either. "I've spent time visiting prisoners," she says. "You're not really ever allowed to ask them what they've done. But they're in prison and they've committed crimes, and the striking thing is that they're just like you and me. They are normal girls." For all her problems, Mortimer believes the same is true of Jessie: "She's trying to suppress this side of her... she's terrified of it. But like anything a person banishes, it comes back to haunt her. The trouble with a lot of films is that they rarely seem to portray people to be as complicated as they are in real life. What I love about this character is that she is a good person who wants to be a kind and loving wife, and at the same time she has a sort of death-wish -- a thirst for danger and a need to put her hand in the fire."

Transsiberian definitely takes audiences in at least one direction that would have even made Hitchcock squirm in his chair: An explicitly gruesome torture scene featuring Sir Ben Kingsley. "The conditions of the filming were just as miserable as the conditions in the scene; we were in a horrible, dusty cold building, and we were all screaming," recalls Mortimer. "It was shocking -- probably the hardest thing I've ever had to shoot. In order to make it believable I had to really go there, but it was so hard to imagine ever being in that situation, and how one would react. I'm so glad that it's in the film, it adds to the weirdness of it, just another reason this isn't just a conventional thriller."

Mortimer is used to filmmakers putting her in awful situations by now; she recently wrapped Shutter Island, the feverishly awaited Scorsese picture about the hunt for a murderess who has escaped a mental institution. It's hard to feel normal afterward, she says, citing her memorable stint on 30 Rock (as Phoebe, she of the "Avian Bone Syndrome") as feeling like a crash-landing after Transsiberian's punishing shoot. "That was the first thing I did when I got back from filming in Lithuania -- I was immediately in a soundstage in New York, dressed in designer clothes and talking pretentiously about poetry and my brittle bones and having sex with Alec Baldwin. It was such a culture shock I couldn't believe it. A good antidote to Lithuania!" She hopes her disorienting experience will rub off on audiences as the film is released nationwide. "If you feel really weird and guilt-ridden after the movie," she laughs, "then it's done its job."