Shutter Island is a thriller written in 2003 by Dennis Lehane. Set in the summer of 1954, with memories of World War Two still fresh, the novel follows U.S. Marshal Teddy Daniels as he travels to Shutter Island, the location of Ashecliffe Hospital for the Criminally Insane. Assigned a new partner, Chuck Aule, Teddy is ostensibly investigating the disappearance of a patient, but is also investigating rumors of Ashecliffe's use of controversial radical treatments. The book has an intriguing and exceptionally intricate plot and the reader is confronted by two equally plausible conclusions at the end.
Shutter Island deals in depth with different psychiatric conditions and disorders, including pure psychopathy, delusions and bipolar disorder. In order to write the novel, Lehane researched psychiatry and mental illness in depth and credits three books in particular for his research: Mad In America by Robert Whittaker, Gracefully Insane by Alex Beam, and Boston Harbor Islands by Emily and David Kale.
Unlike Lehane's other works—which take place in the Boston area and deal with many of the social issues facing the poor white residents of Southie and Dorchester, like child abuse, gentrification, and drugs—Shutter Island takes place off the coast of Boston, and in the past. Nonetheless, throughout the novel, Lehane draws on Boston's history, including its past in the Revolutionary and Civil Wars, as well as the military's use of islands off the coast of Massachusetts as target practice for shelling in the Pacific Theater. Boston's tense racial history, too, is also reflected in the island's staff.
The book was national bestseller, and, after the success of the 2003 film adaptation of Lehane's Mystic River, led to even greater national exposure for the author. Lehane wrote several episodes for the HBO series "The Wire" soon after, and in 2010, Shutter Island was turned into a film by Martin Scorsese, starring Leonardo DiCaprio and Mark Ruffalo.