The mentally ill patients in Amberly Secure Unit are highly suggestible. When unexplained power cuts lead to a series of horrifying incidents, fear spreads from the inmates to the staff. Amidst the growing hysteria, AJ, a senior psychiatric nurse, is desperate to protect his charges. Detective Inspector Jack Caffery is looking for the corpse of a missing woman. When AJ seeks Caffery's help in investigating the trouble at Amberly, each man must face a bitter truth in his own life.