In the frigid clime of Tumba, Sweden, Detective Inspector Joona Linna has been assigned to a gruesome triple homicide. The killer is still at large, and there’s only one surviving witness --- the boy whose family was killed before his eyes. With one hundred knife wounds on his body, the boy lies in a state of shock, scared into silence. Linna sees only one option: hypnotism. He enlists Dr. Erik Maria Bark to mesmerize the boy, hoping to discover the killer through his eyes. It’s the sort of work that Bark has sworn he would never do again --- ethically dubious and psychically scarring. When he breaks his promise and hypnotizes the victim, a long and terrifying chain of events begins to unfurl.