Detective Murdoch investigates the murder of Alexander Taylor who is found in his living room on his birthday obviously having been attacked with a ax. The case seems open and shut however when they find the man's daughter Charlotte sitting on her bed with the murder weapon in her hands. Charlotte admits that she must have killed her father but has no memory of it. She also says she often has no memory when she is possessed by the devil. During an interrogation however another character, Maddie, emerges leading Murdoch to conclude that there are two personalities in the same body. He consults Dr. Roberts, who has helped him in the past, who recommends they try hypnosis. What they find is that she has more than two personalities. But which one committed, or perhaps witnessed, the crime?