Shutter Island

Shutter Island is a film from 2010 starring Leonardo Dicaprio as the main character, Teddy Daniels, a U.S. marshal. The year is 1954, and he is assigned to investigate the disappearance of a patient from Boston's Ashecliffe Hospital located on a mysterious island called Shutter Island. He's been pushing for an assignment on the island for personal reasons, but before long he wonders if he has been brought there as part of a twisted plot by hospital doctors whose strange treatments are unethical and sinister. Teddy's clever investigating skills soon provide a promising lead, but the hospital refuses him access to records he suspects would give him more information about the case. As a hurricane cuts off communication with the mainland, more dangerous criminals try to escape in the confusion, and the puzzling clues multiply, Teddy begins to doubt everything - his memory, his partner, even his own sanity.

In the end, a major plot twist is revealed. It turns out that "Teddy" is actually a delusional mental patient in the hospital, not a U.S. marshal. He murdered his depressed wife Dolores Chanal after she drowned their three children. Because he was a mental patient at the hospital, the doctors decided to try a role-play experiment to allow him to live out his delusional fantasy in order to come to terms with reality. The treatment plan works, and he is retold what has happened to him and he accepts what he did to his wife. However, in the final scene he relapses to a delusional state. It is implied that he is faking his relapse so he will not have to deal with the mental suffering of his act, because he feels personally responsible for his wife murdering their children.