This gruesome psychological shock fest has the most horrific premise so far this year. Two men (Cary Elwes and one of the film’s co-writers, Leigh Whannell) wake up shackled to pipes in opposite corners of a large, dilapidated bathroom that houses a filthy toilet and bathtub. A dead body lies in a pool of blood between the two men. Beside the corpse lie a tape recorder and a handgun. Their captor has left separate taped messages that include instructions of what one man must to do within four hours to save the lives of his kidnapped wife and child. A parallel cliché-filled story also unfolds, in which two detectives (Danny Glover and Ken Leung) race against time to nab a serial killer who devises very elaborate plans in which his victims must make grisly choices to save their own lives. The setup is gripping, and the suspense intense, but the third act—the payoff for sitting through such harrowing material—is a major misfire.