Set in 1954, the film follows U.S. Marshal Teddy Daniels (Leonardo DiCaprio) and his partner Chuck Aule (Mark Ruffalo) as they investigate the disappearance of a patient from Ashecliffe Hospital, a psychiatric facility located on Shutter Island. As they delve deeper into the case, Teddy uncovers disturbing secrets about the institution and its treatments. Haunted by his own traumatic past and visions of his deceased wife (Michelle Williams), Teddy begins to question his sanity and reality itself. The film is a psychological thriller filled with twists, culminating in a shocking revelation that challenges everything Teddy believes.