Leonard Shelby is tracking down the man who raped and murdered his wife. The difficulty of locating his wife's killer, however, is compounded by the fact that he suffers from a rare, untreatable form of short-term memory loss. Although he can recall details of life before his accident, Leonard cannot remember what happened fifteen minutes ago, where he's going, or why.

A young man struggles to access sublimated childhood memories. He finds a technique that allows him to travel back into the past, to occupy his childhood body and change history. However, he soon finds that every change he makes has unexpected consequences.

With his wife's disappearance having become the focus of an intense media circus, a man sees the spotlight turned on him when it's suspected that he may not be innocent.