Summer, 1954. US Marshal Teddy Daniels has come to Shutter Island, home of Ashecliffe Hospital for the Criminally Insane. Along with his partner, Chuck Aule, he sets out to find an escaped murderess named Rachel Solando as a hurricane bears down upon them.

But nothing at Ashecliffe Hospital is what it seems. And neither is Teddy Daniels. Is he there to find a missing patient? Or has he been sent to look into rumours of Ashecliffe's radical approach to psychiatry? As the investigation deepens, the questions mount. How has a barefoot woman escaped an island from a locked room? Who is leaving them clues in the form of cryptic codes? And what really goes on in Ward C?

The closer Teddy and Chuck get to the truth, the more elusive it becomes, and the more they begin to believe that they may never leave Shutter Island. Because someone is trying to drive them insane...