Young British filmmaker Christopher Nolan is quickly developing into a master of a genre one might call "the puzzle movie," pictures that play with time and the amount of information that's parceled out to the audience. Citizen Kane, of course, is a landmark in this area, and experiments with time enjoyed a particular heyday in the '60s with films like Alain Resnais' Muriel and Richard Lester's Petulia. In the '90s, Quentin Tarantino scored his biggest success with the triptych games of Pulp Fiction. Now comes Nolan, who made a very impressive debut two years ago with the low budget Following, the story of an unemployed writer obsessed with following strangers, which revealed its narrative surprises through flashbacks and flash-forwards.

Nolan's second feature, Memento, is even trickier. Guy Pearce (the straight-arrow cop in L.A. Confidential) stars as Leonard Shelby, a young businessman whose wife has been murdered and who was beaten so badly during the incident, he now suffers from permanent short-term memory loss. Leonard is determined to find his wife's killer--a rather quixotic goal when you can't remember what happened 15 minutes ago. Leonard holds onto and pieces together what he's learned by taking Polaroid snapshots, scribbling notes, and even tattooing crucial information onto his body. The entire film is told from Leonard's point of view, and Nolan finds a stylistic correlative for his hero's disorientation by arranging the scenes in backward chronology; in other words, every scene depicts what happened before the previous one. As in Harold Pinter's Betrayal (and the memorable "Seinfeld" episode it inspired), more and more "deep background" is revealed as the story goes on, with the audience becoming increasingly aware of the ironies and futilities of the action onscreen.

Nolan adapted his screenplay from a short story by his brother Jonathan, and their handiwork is ingenious. Like Leonard, you're never quite certain whom to trust. Is Leonard's self-appointed buddy, the brash and vaguely sleazy Teddy (Joe Pantoliano), a true ally or a double-crossing con man? ("Don't believe his lies," Leonard scribbles on a Polaroid of Teddy.) Does Natalie (Carrie-Anne Moss), the sultry barmaid with man troubles of her own, really love and want to protect Leonard? Memento is forever confounding your expectations; the movie forces you to work, but any puzzle addict will be exhilarated by the effort. The startling wrapup to the story may not be to everyone's taste, but it's certainly consistent with the movie's disruptive agenda.

Australia's Pearce, seen here with bleached-blond hair and again managing a good American accent, holds this demanding film together with his alternately tough and vulnerable portrayal of a truly lost soul. Leonard, a cipher even to himself, is a tremendously difficult role, but Pearce fills it with passion, poignance and even some touches of absurdist humor. (At one point, Leonard forgets whether he's chasing someone or being chased.) Moss, the lead action heroine in The Matrix and currently acting prim in Chocolat, finds just the right balance for her mysterious femme fatale, and the dependable Pantoliano, another Matrix veteran, brings his trademark energy and humor to the equally ambiguous Teddy.

Like The Usual Suspects of a few years back, Memento is the kind of movie that almost demands a repeat viewing. At the very least, it's a guaranteed best-seller on DVD, where viewers can rearrange scenes at the touch of a button.

-Kevin Lally