''I can't make new memories,'' explains Leonard Shelby (Guy Pearce), the vengeance-seeking insurance investigator at the center of ''Memento,'' Christopher Nolan's ingenious new thriller. The line, which Leonard repeats over and over, since he can't remember whether he's told anyone before, has the spooky resonance of Haley Joel Osment's claim, in ''The Sixth Sense,'' to be able to see dead people.
Leonard's malady, which in a weird way is also something of a gift, is neurological rather than metaphysical, but like M. Night Shyamalan, Mr. Nolan uses it to generate mystery, surprise and a series of clever epistemological puzzles. ''Memento'' is like an existential crossword puzzle, or a pungent 50's B-thriller with a script by Jorge Luis Borges.
The film's story and setting are boilerplate noir. Leonard, attired in an expensive silk suit, cruises a bleached-out Southern California landscape of anonymous motels and abandoned warehouses in a desperate search for the man who raped and murdered his wife.
Though Leonard retains a clear memory of his life before the crime -- and flashes back periodically to the event itself -- his life since has been a series of disconnected, forgotten and therefore repeated moments. Time is supposed to heal all wounds, but since Leonard is unable to experience the passage of time, his hurt remains raw and unassuaged.
To aid him in his quest he carries around a sheaf of Polaroids, and when he is really sure of a piece of information he has it tattooed on his body, which stands in for the damaged part of his mind. His indelibly marked torso is the repository of his grief, his rage and his reason to go on living.
The reason to go on watching ''Memento,'' which begins with a killing and its aftermath shown in reverse (an instant photograph fades to white, a bullet flies out of a man's head and back into the chamber of a gun), is for the disorienting pleasure of its unusual narrative technique. The audience is plunged into a condition analogous to Leonard's, but also, logically speaking, the opposite.
He lacks all recollection of the past, and so in compensation we are given memories of his near future. The story is told in a lurching backward motion: Each scene jumps back in time, and ends where the previous one -- in narrative time, the next one -- began. Before too long you get the hang of looking for causes that follow from effects. If you notice a scar or a bruise on a character's face, before long you'll see the punch that put it there.
Aiding Leonard in his quest, or perhaps using the blank slate of his mind for their own ulterior purposes, are a cheerful fellow named Teddy (Joe Pantoliano), the dead man in the opening scene, and a glum bartender named Natalie (Carrie-Anne Moss). Leonard's meetings with them have a jagged comic rhythm, since he can never be sure, without rifling through his snapshots, that he's met them before.
These encounters, which give the otherwise simple plot a dizzying feeling of complication, alternate with black-and-white scenes of Leonard in his motel room, explaining the meaning of a tattoo on his hand that says ''Remember Sammy Jankis.''
Sammy (Stephen Tobolowsky), whose story is also glimpsed in black and white, though related in normal chronological order, was the subject of one of Leonard's investigations and suffered from a similar malady. But while Leonard recalls Sammy's sad tale perfectly, he seems unable to grasp its moral or its relevance to his own case.
Mr. Pearce, whose tight, tricky performance in ''L.A. Confidential'' was somewhat lost in the hoopla surrounding Kevin Spacey and Russell Crowe, occupies nearly every frame of ''Memento'' and succeeds in the difficult task of portraying a man at once utterly clueless and fanatically sure of himself.
Though Leonard has bouts of melancholy and episodes of panic, he seems almost blithe in his interactions with Natalie and Teddy. His nervous, ingratiating manner is that of someone feeling out a new situation. He can never get used to anything, except the endless repetition of first impressions, which he tries to turn into facts.
Mr. Pantoliano and Ms. Moss both rise in different ways to the equal challenge of playing off Leonard's hyperactive disconnection. Teddy tries to put Leonard at ease by teasing him, whereas Natalie affects a weary, sympathetic tolerance.
''Memento'' is a brilliant feat of rug-pulling, sure to delight fans of movies like ''The Usual Suspects'' and ''Pi.''
Like Darren Aronofsky (who directed ''Pi'' and last year's ''Requiem for a Dream''), Mr. Nolan demonstrates a supercharged cinematic intelligence. He's clearly excited by the way the medium can manipulate time and information, folding straightforward events and simple motives into Möbius strips of paradox and indeterminacy.
But though ''Memento'' is impressive, it doesn't in the end leave much of an impression. Like a day in Leonard's life, it slips easily from memory, favoring sensation over insight and the frisson of artificial confusion over any contemplation of human reality.
Leonard's tattoos and photographs are a poor and unreliable substitute for the thick confusion of memory, and ''Memento,'' for all its undeniable formal dazzle, is a triumph of mind in the absence of matter.
''Memento'' is rated R (Under 17 requires accompanying parent or adult guardian). It has violence and profanity.
MEMENTO
Written and directed by Christopher Nolan; based on a short story by Jonathan Nolan; director of photography, Wally Pfister; edited by Dody Dorn; music by David Julyan; production designer, Patti Podesta; produced by Jennifer Todd and Suzanne Todd; released by Newmarket Group. Running time: 118 minutes. This film is rated R.
WITH: Guy Pearce (Leonard), Carrie-Anne Moss (Natalie), Joe Pantoliano (Teddy), Mark Boone Junior (Burt), Stephen Tobolowsky (Sammy), Jorja Fox (Leonard's wife) and Harriet Harris (Mrs. Jankis).