Dementia 13 (known in the United Kingdom as The Haunted and the Hunted) is a 1963 independently made black-and-white horror-thriller film, written and directed by Francis Coppola and produced by Roger Corman. The film stars William Campbell, Patrick Magee, and Luana Anders. It was released in the United States by American International Pictures during the fall of 1963 as the bottom half of a double feature with Corman’s X: The Man with the X-ray Eyes.
While out rowing in the middle of a lake after dark, John Haloran and his young wife Louise argue about his rich mother’s will. Louise is upset that everything is currently designated to go to charity in the name of a mysterious “Kathleen.” The argument, combined with the exertion of rowing the boat, causes John to have a heart attack. He informs Louise that, should he die before his mother, Louise will receive none of the inheritance, after which he promptly dies. Thinking quickly, the scheming Louise dumps his fresh corpse over the boat’s side, where it sinks to the bottom of the lake. Her plan is to pretend that he is still alive so that she can ingratiate her way into the will. She types up a letter to her mother-in-law, Lady Haloran, inviting herself to the family’s castle in Ireland while her husband is “away on business.”
At the castle, she immediately notices that things are a little odd. John’s two brothers, Billy, and Richard, take part in a bizarre, ritualistic ceremony with their mother, part of a yearly tribute to their deceased younger sister Kathleen, who died years before in a freak drowning accident. Lady Haloran still mourns for her daughter, and during the ceremony, she faints dead away as she does every year. As Louise helps her mother-in-law into the castle, Lady Haloran tells her that she fainted because one of the fresh flowers she had thrown died as it touched Kathleen’s grave.
Louise, realizing that Lady Haloran is emotionally overwrought and superstitious, devises a plan to convince the old woman that Kathleen is trying to communicate with her from beyond the grave. The plan involves stealing some of the dead girl’s old toys and placing them at the bottom of the estate’s pond, where they will float to the surface in a ghostly way during the middle of the day. That night, Louise swims underwater and begins placing the toys, as planned. She is shocked to see what appears to be Kathleen’s perfectly preserved corpse at the bottom of the pond. Horrified, she surfaces and is abruptly attacked with an axe by an unknown assailant; her killer drags Louise’s bloody corpse away.
Concerned family doctor Justin Caleb arrives and becomes determined to solve the mystery. He intensely questions the family. The murderer, meanwhile, strikes again, decapitating a man named Simon, who has been poaching on the estate. Dr. Caleb has the pond drained, revealing a stone statue shrine, engraved with the words “Forgive Me, Kathleen.” The following night, Lady Haloran is attacked by a shadowy figure, but she eludes him and collapses in the castle’s courtyard.
Dr. Caleb finally uses an obscure nursery rhyme (“Fishy, fishy, in a brook, Daddy caught you on a hook”), recited by Billy under hypnosis, to help him discover Louise’s frozen corpse hidden away in a meat locker. Next to the bloody body is a wax figure of Kathleen. Dr. Caleb places the figure in a public square to lure out the killer. Taking the bait, a gibbering Billy, who has gone insane with guilt over causing the death of his sister Kathleen, attempts to kill Richard’s fiancée Kane with an axe. Dr. Caleb saves her life by shooting Billy to death with a pistol he was carrying in his pocket.