A clearly disturbed young woman possessed of four personalities takes an axe to her abusive father possibly because of a trauma suffered seventeen years earlier.

Detective Murdoch investigates the death of Nurse Collins who seems to have been killed by a patient, Rose Maxwell, at the insane asylum where Dr. Ogden works. Somehow, the extremely violent Rose managed to get out of her room and knock out the guard, Samuel Drainie. It appears she then used his knife to stab nurse Collins 11 times; there were also bite marks on the body. Rose, who killed her entire family, also blames Dr. Ogden and Dr. Grace for her current predicament and has vowed revenge. Crabtree finds all of the women's fingermarks on the murder weapon but it's the frequent visits from Rose's brother Cedric that initially draws his attention. The solution to the mystery lies elsewhere however.