Leonard Shelby wears expensive, tailored suits, drives a late model Jaguar sedan, but lives in cheap anonymous motels, paying his way with thick wads of cash. Although he looks like a successful business man, his only work is the pursuit of vengeance: tracking and punishing the man who raped and murdered his wife. His suspicions dismissed by the police, Leonard's life has become an all-consuming quest for Justice.
The difficulty, however, of locating his wife's killer is compounded by the fact the Leonard suffers from a rare, untreatable form of memory loss. Although he can recall details of his life before his "accident," Leonard can't remember what happened fifteen minutes ago, where he is, where he is going, or why.