"Memories are just an interpretation, not a record. Facts are facts." That's what Leonard Shelby (Guy Pearce), an insurance claims investigator, keeps repeating to himself as he recalls discovering his wife sprawled on their bathroom floor and then being hit on the head from behind. That blow caused a permanent condition called short-term memory loss, meaning that, while he can draw on memories from before the accident, Leonard cannot recall what happened from one moment to another since. He constantly forgets what he's doing, where he's going and whom he can trust. To maintain some semblance of order in his life, he snaps Polaroid photos of people he meets, jotting cautionary captions on each, like "Don't believe his lies." For other pertinent information, he tattoos his body, like "John G. raped and murdered my wife" on his chest. Which is important, because Leonard's determined to avenge his wife's death. Writer/director Christopher Nolan, working from his brother Jonathan Nolan's short story and with cinematographer Wally Pfister, tautly alternates color with black-and-white sequences to reveal Leonard's recollections backwards. Jumbled imagery fits together like pieces of an intricate jigsaw puzzle, and the audience is as confused as Leonard. As the brain-damaged protagonist, Guy Pearce ("L.A. Confidential") delivers an ironic, tour-de-force performance, particularly playing off Carrie-Ann Moss, who enjoys messing with his mind, and Joe Pantoliano, who could be either a friend or foe. On the Granger Movie Gauge of 1 to 10, "Memento" is an edgy, disconcerting 9. It's a weird, murky thriller that toys with your mind, culminating in an unsettling universal truth, as Leonard admits, "I have to believe that, when my eyes are closed, the world's still here."