You think I’m mad, don’t you? They all thought I was mad when I said he killed my daddy. Paul Decker (Peter van Eyck) kills his wealthy wife by gassing her in the living room of their luxury Italian villa. He survives in the sealed room by hiding under the floorboards with a snorkel. The police assume it’s a suicide: Paul has an alibi from a sojourn just across the border in France. Paul’s stepdaughter Candy (Mandy Miller) suspects he has murdered her mother – she says she saw him hold her father underwater and kill him too. Her dog Toto agitates Paul by playing with the snorkel which he finds in his hotel room and Paul poisons him. Candy is convinced he did it deliberately but her companion Jean (Betta St John) thinks she has a psychiatric disorder. Paul starts to seduce Jean and persuade her that Candy is mad. It’s only a matter of time before Paul tries to kill Candy too … An effective thriller from the House of Hammer, adapted from the story by Anthony Dawson (the crim who gets scissored by Grace Kelly in Dial M for Murder) by the man who would become a studio stalwart, Jimmy Sangster (and Peter Myers). The tension is nicely sustained in this slice of Gothic and Miller is excellent as the teen who persists with her suspicions. The dog is great! Produced by Michael Carreras and directed by Guy Green.