Shutter Island is Martin Scorsese's fourth collaboration with Leonardo DiCaprio and, at the time of its release, produced his biggest opening weekend in history. Released on February 19, 2010 — after premiering at the Berlin Film Festival on February 13 — the film earned $41 million in its domestic opening weekend and went on to gross $294.8 million worldwide against an $80 million budget. It remains Scorsese's highest-grossing film until The Wolf of Wall Street, the project he and DiCaprio had originally planned to make before Shutter Island intervened. Both Josh Brolin and Robert Downey Jr. were considered for the lead role before DiCaprio was cast. The screenplay was adapted by Laeta Kalogridis from Dennis Lehane's 2003 novel — the same Lehane who wrote Mystic River and Gone Baby Gone — and the production used the abandoned Medfield State Hospital in Massachusetts for multiple locations, using production design tricks to make different sections of the building look like separate places. Cinematography was by Robert Richardson, a three-time Oscar winner who brought the film's oppressive weather and institutional dread to life with handheld work and expressionistic lighting. Thelma Schoonmaker, Scorsese's editor on every major film since Raging Bull, assembled the film's disorienting structure. The film is rated R and runs 2 hours and 18 minutes. Its music supervision was handled by Robbie Robertson, Scorsese's longtime musical collaborator. The film was selected by the National Board of Review as one of the top ten films of 2010.

The story is set in 1954 and follows U.S. Marshal Edward 'Teddy' Daniels, played by DiCaprio, and his new partner Chuck Aule (Mark Ruffalo) as they arrive by ferry at Ashecliffe Hospital for the Criminally Insane on Shutter Island, off Boston Harbor. They have been sent to investigate the disappearance of Rachel Solando, a patient who had drowned her three children and then apparently escaped her locked room without leaving footprints. Dr. John Cawley, the hospital's chief psychiatrist played by Ben Kingsley, is the genial but guarded host of the investigation. His German colleague Dr. Jeremiah Naehring, played by Max von Sydow, raises Teddy's immediate suspicion — partly through the kind of smooth, psychologically probing behavior that Teddy associates with manipulation, and partly because his German accent connects in Teddy's trauma to the liberation of Dachau in 1945, which Teddy participated in as a soldier and which haunts him in recurring flashbacks. Emily Mortimer plays the version of Rachel Solando presented to Teddy by the staff — a fragile, clearly disturbed patient who is eventually 'recaptured.' Patricia Clarkson plays a different, lucid woman who claims to be the real Rachel Solando, discovered by Teddy hiding in a cave on the island's cliffs. She tells him the hospital is conducting illegal experiments and that the entire investigation is a performance designed to disorient him. George Noyce, played by Jackie Earle Haley, is a patient in the feared Ward C who gives Teddy a similar warning, telling him that nothing on the island is what it seems and that Shutter Island is a place people come to but don't leave. Ted Levine plays the Warden, a cold and menacing figure who appears briefly but memorably. Teddy's dead wife Dolores, played by Michelle Williams, appears in dreams and hallucinations — warm, loving, and decomposing in turns — as the film's emotional anchor for what Teddy has lost.

The film's two major secrets are deeply intertwined. The first is that Chuck Aule is not a real marshal: his true identity is Dr. Lester Sheehan, Teddy's actual treating psychiatrist at Ashecliffe, who has been playing the role of partner as part of a therapeutic role-play designed and overseen by Dr. Cawley. The second secret is Andrew Laeddis. Teddy Daniels is not a real person — he is a constructed identity, an anagram and an escape mechanism created by Andrew Laeddis, patient number 67 at Ashecliffe, who was committed after he killed his wife Dolores following her murder of their three children by drowning them in the lake behind their home. Dolores was manic-depressive and had been hospitalized twice before; she killed the children during one of her episodes while Andrew was away. Andrew returned, found the children dead in the lake, held Dolores, and then shot her. The guilt was unbearable, and Andrew's mind constructed the Teddy Daniels persona to allow him to live inside a false history in which Dolores died in a fire set by the arsonist 'Andrew Laeddis' — making himself the villain of a separate story rather than the husband who failed to protect his family. The names themselves contain a clue: Dolores Chanal and Rachel Solando are exact anagrams of each other — the fake patient Teddy is supposedly investigating is built from the letters of his dead wife's name. Andrew Laeddis and Edward Daniels are also anagrams of each other. These details are hidden in plain sight throughout the film but only become visible in retrospect, which is exactly the effect Scorsese intended.

The therapeutic role-play that constitutes most of the film's plot was Dr. Cawley's last attempt to break through Andrew's delusion without resorting to lobotomy. The entire investigation — the missing patient, the ferry ride, the storm, the cave encounter, the lighthouse — was staged by the hospital staff as an immersive scenario designed to let Andrew work through the logic of 'Teddy Daniels' until it collapsed under its own weight. If Andrew could confront the truth of who he was and what he had done, Cawley believed he could be treated. If not, the only remaining option was a surgical procedure that would destroy him a different way. The film's final scene shows Andrew apparently lucid — sitting with Dr. Sheehan on the hospital steps, seemingly accepting his identity as Andrew Laeddis. Then he calls Sheehan 'Chuck,' reverts to the Teddy persona, and asks to be taken to the lighthouse. The question of whether this is a relapse or a deliberate choice is the film's most contested point. The final line — 'Which would be worse: to live as a monster, or to die as a good man?' — suggests Andrew may be choosing lobotomy consciously, preferring the clean erasure of himself to the unbearable clarity of living with what he knows. Scorsese and DiCaprio have both said in interviews that they believe Andrew made a conscious choice — that the final version of Teddy Daniels is a decision rather than a breakdown. The film leaves both readings intact. Robert Richardson's cinematography throughout the film uses a deliberately hypnagogic color palette for the dream sequences, saturating them with warmer, more lurid tones to distinguish them from the cold, overcast daylight of the island — a visual system that rewards second viewings.