Leonard is an insurance investigator whose memory has been damaged following a head injury he sustained after intervening on his wife's murder. His quality of life has been severely hampered after this event, and he can now only live a comprehendable life by tattooing notes on himself and taking pictures of things with a Polaroid camera. The movie is told in forward flashes of events that are to come that compensate for his unreliable memory, during which he has liaisons with various complex characters. Leonard badly wants revenge for his wife's murder, but, as numerous characters explain, there may be little point if he won't remember it in order to provide closure for him. The movie veers between these future occurrences and a telephone conversation Leonard is having in his motel room in which he compares his current state to that of a client whose claim he once dealt with.