After wandering for many years through the dark alleys of the American city and exploring in the violent lives of urban loners, ethnic underdogs, gangsters, and cops, in "Shutter Island" Martin Scorsese turns to a different place and a fresh subject. In the new movie, the director deals with the elements and the genre of mystery and horror in the isolated setting favored by specialists in dread and gore. Although avoiding the disembowelments and decapitations that adorn contemporary versions of the form, the movie generates enough unpleasantness to satisfy both bloodthirsty fans and serious students; on the other hand, its downbeat conclusion may also disappoint audiences seeking neat solutions to its mystery and a final relief from horror.

Announcing the date as 1954, the picture opens with federal marshal Teddy Daniels (Leonardo DiCaprio), seasick on the ferry transporting him and his sidekick Chuck (Mark Ruffalo) to the title location, a foreshadowing of the pain and discomfort he will suffer throughout the story. He and Chuck journey to Shutter Island to investigate the disappearance of a patient named Rachel Solando from the hospital for the criminally insane that occupies the entire island. A self-contained government facility, the place resembles a fortress or a prison more than a hospital - armed guards patrol the grounds, electrified fences prevent any escapes, many of the patients wear shackles, and the investigators confront stonewalling and silence from employees and patients.

The smooth, patronizing chief psychiatrist, Dr. Cawley (Ben Kingsley), gives them some minimal background information on the missing woman, who murdered her three children, but, citing hospital regulations, forbids them access to patient records. They interview staff and patients, all of them reluctant to talk and none of them helpful, learning little beyond the realization that it seems impossible for anyone to escape from the heavily guarded and entirely isolated place.

Complicating matters more, Daniels suffers debilitating migraines accompanied by memories of his wife, who died in a fire, and flashbacks to his experience in the war, when he participated in the liberation of Dachau. Along with the memories, his headaches also stimulate a series of dreams and hallucinations, some of them occurring within other dreams, confusing both the detective and the audience. The puzzles proliferate as he and his assistant find evidence of an involved series of conspiracies appropriate to the time, and encounter a number of scary people who either threaten them with harm or warn them to flee the island.

Despite a long and repetitive plot, the unusual physical setting and the human context create a good deal of suspense and shock - the spooky buildings, the endless dismal corridors, the menacing patients, the sinister doctors and nurses combine to obscure the investigation and threaten the safety of the marshals. Even the weather conspires against the detectives when a violent storm strikes the island, cutting them off entirely from any communication with the mainland and establishing the climactic confrontation that, sadly and perhaps disappointingly, solves all the puzzles.

"Shutter Island" devotes too much of its time to several long conversations about the real puzzles of Shutter Island, which include CIA drug experiments, new weapons to fight the Soviet Union, prefrontal lobotomies, and discussions of modern psychiatric theory and practice. The talky and essentially preposterous script sometimes bogs down under the weight of the prolix dialogues, the artificial exposition, and the lengthy explanations of characters and action, all of which hint at the reasons for the movie's long-delayed opening.

DiCaprio's exaggerated acting - he behaves almost hysterically from the opening moments, before he encounters any reason for it - mostly suits the melodramatic style of the whole work, but he seems too callow for the physical and emotional state of his character. His struggles through the rugged landscape of Shutter Island, his repeated pursuits and flights through the gloomy passageways and staircases of the hospitals, the overwhelming sense of claustrophobia hint at the tangled puzzle of his investigation and the tragic labyrinth of his own mind. Whatever its faults, the picture quite faithfully follows Dennis Lehane's novel and, not surprisingly considering the director, achieves a genuine sense of fright and, for a horror film, a most unusual sadness.