I'll get to the point: The main, if not only, reason to see ''The Machinist" is for Christian Bale's title performance, and even then you have to be a fan of hardcore martyrdom in the service of craft.
As Trevor Reznik, a machine-shop tool operator who hasn't slept in more than a year, Bale is a frighteningly gaunt shadow of his usual self. His eyes are far back in his sockets, staring paranoically; his bones seem ready to break through skin. Every step seems like agony. The actor dropped 60 pounds to bottom out at 130, a feat that goes beyond De Niroesque transformation into the valley of masochism. Says one of Trevor's co-workers, ''If you were any thinner, you wouldn't exist."
Sadly, the same has to be said about the movie, a stylish but fatally shallow puzzler that suggests a ''Twilight Zone" episode filmed on the leftover sets of ''Seven."
The factory where Trevor works is a dank no-man's-land of rusted steel and welding sparks, a place where everyone is a candidate for Industrial Accident of the Week. The unlucky winner early on is Miller (Michael Ironside), a gruff press operator who loses his arm to one of the machines, and while Trevor's co-workers blame him, Trevor is sure a hulking character named Ivan is responsible. No one has actually seen Ivan, though, so obviously it's part of a plot to drive the hero crazy.
Back at his dungeon of an apartment (decor by early David Lynch), Trevor's consolations are few. He has a girlfriend of sorts in hooker-next-door Stevie, which is such a Jennifer Jason Leigh role that the filmmakers have thrown up their hands and hired Jennifer Jason Leigh. He also nurses a shy crush on Marie (Spanish actress Aitana Sanchez-Gijon), a diner waitress and single mom to Nicholas (Matthew Romero Moore), who Trevor unwisely takes on an amusement park horror ride in one of the more unnerving sequences in ''The Machinist."
One of the reasons the film is so thick with art-directed dread is that director Brad Anderson (''Next Stop Wonderland," ''Session 9") has little to work with in the way of story. As Trevor spirals downward into insomnia and terror, he becomes obsessed with tracking Ivan, who drives around cackling in a red convertible. That and the melting of the line between reality and hallucination are the only action during the film's back nine, and while Trevor can't figure out what's happening, you very probably will. Like the films of M. Night Shyamalan, ''The Machinist" needs a payoff commensurate with its set-up, and like ''The Village," it doesn't deliver.
You're left, then, with the spectacle of Bale as a human skeleton, a remarkable but pointless stunt that increases your admiration for the actor at the same time it leaves you questioning his choices. Over the course of his singular career -- which started in adolescence with the lead role in Spielberg's ''Empire of the Sun" -- Bale has seemed both daring and utterly humorless, a combination that leads him to treat the pitch-black farce of ''American Psycho," the silly futurism of ''Equilibrium," and the gonzo B-movie action of ''Reign of Fire" as if they were one and the same film.
He's due up next in the title role of summer 2005's ''Batman Begins," and hopefully he'll have stopped by the catering truck for a Danish before then. Maybe he'll have learned to lighten up a little, too, but I doubt it; that jawline was made for the Dark Knight's somber rectitude. Bale's creative commitment is beyond reproach and so is his performance here, but starving himself for something as minor as ''The Machinist" goes beyond foolhardy and into the vaguely tasteless.
Ty Burr can be reached at email@example.com.