Set in 1954, Dennis Lehane’s psychological thriller Shutter Island follows U.S. Marshal Edward “Teddy” Daniels and his new partner, Chuck Aule, as they arrive at Ashecliffe Hospital for the criminally insane on a remote island in Boston Harbor. Their mission is to investigate the impossible disappearance of patient Rachel Solando, who vanished from a locked room, leaving behind only a cryptic riddle.
As a hurricane cuts off communication with the mainland, Teddy discovers that Ashecliffe is a haunting place surrounded by secrets. While conducting his investigation, he struggles with his own trauma, including vivid, harrowing nightmares of his late wife, Dolores Chanal, who perished in an apartment fire allegedly set by a man named Andrew Laeddis. Teddy reveals to Chuck that he specifically took this assignment to find Laeddis, whom he believes is an inmate on Shutter Island.
Throughout the investigation, the hospital staff—led by the enigmatic Dr. John Cawley—appear evasive, withholding patient files and acting in a way that suggests a conspiratorial cover-up. Teddy begins to suspect the institution is running unethical experiments, perhaps even using psychological torture to turn patients into “ghost” assassins. As paranoia sets in, Teddy suspects his partner is being influenced by the staff, and his sanity begins to unravel.
The investigation leads Teddy to Ward C, the maximum-security unit, where he faces hostility from the patients and staff. After falling, he finds his way to a cave where another woman, claiming to be the real Rachel Solando, tells him that the hospital is trying to make him think he is insane, a common tactic on the island to discredit whistleblowers.
Written in 2003, the novel’s, the final twist takes place in the island’s lighthouse and reveals that the “conspiracy” is actually a radical role-playing therapy experiment created by Dr. Cawley. Teddy is not a U.S. Marshal; he is actually Andrew Laeddis, the 67th and most dangerous patient on the island, who has been in denial about his real actions for two years. The fake Rachel Solando was a test to break through his delusion, and “Chuck Aule” was actually his primary psychiatrist, Dr. Lester Sheehan.
It is revealed that Andrew’s wife, who was mentally ill, drowned their three children. Upon discovering this, Andrew shot her and could not handle the guilt. The “investigation” was a last-ditch effort to keep Andrew from being lobotomized. While Andrew briefly regains his sanity, he pretends to relapse, choosing to “die a good man” (by undergoing the lobotomy) rather than “live as a monster.”