Shutter Island

In 1954, U.S. Marshals Edward "Teddy" Daniels and his new partner, Chuck Aule, travel to the Ashecliffe Hospital for the criminally insane on Shutter Island in Boston Harbor. They are investigating the disappearance of patient Rachel Solando, who was incarcerated for drowning her three children. Their only clue is a cryptic note found hidden in Solando's room: "The law of 4; who is 67?" They arrive just before a storm hits, preventing their return to the mainland for a few days. Read more on Wikipedia.