Music video director Simon Brand makes an impressively taut debut with "Unknown," a nifty little psychological crime thriller that suggests a "Treasure of the Sierra Madre" for the postindustrial age.

A nameless man wakes up on the floor of a cluttered, abandoned warehouse; he's surrounded by four other men who have been, respectively, shot, tied up, beaten and otherwise roughly treated. As the men proceed to come to, they realize they're all amnesiac. (In the struggle, a toxic gas was released from a falling tank.) As they sort out who are the bad guys and who are the good guys, "Unknown" becomes a study in primitive motivations, essential natures and shifting alliances. The existential question "Who am I?" takes on not just literal but deeply moral implications as the lead protagonist, played by James Caviezel, tries to sort out which side he's on.

Working from a screenplay by Matthew Waynee, Brand does a good job of doling out crucial information at opportune moments. The premise, while kooky, never feels forced, and bits of humor even burble up amid the despair. Caviezel, Joe Pantoliano, Barry Pepper, Jeremy Sisto and Greg Kinnear (the hardest-working man in show business this year) deliver a fine ensemble performance as five scorpions in a jar.

-- Ann Hornaday

Contains profanity and graphic violence.