Good suspense movie highlighted by Peter Van Eyck as a man who sets up the perfect murder. Mandy Miller is the stepdaughter determined to bring him down.
In their Italian villa, Paul Decker (Peter Van Eyck) tapes the doors and windows and turns on the gas while his wife Madge is out on the couch thanks to some drugged milk. He dons a snorkel and hides under the floor. There’s a trap door with a rug over it. The death is ruled a suicide.
Teenage stepdaughter Candy (Mandy Miller) and Jean Edwards (Betta St.John) the adult hired to be her companion arrive from England. Candy says years ago Paul killed her father and made it look like a drowning accident. Now she says she’s sure Paul killed her mother.
No one believes her as there’s no way she can prove it. Her dog Toto is suspicious. He was sniffing at the rug but no one paid any attention. At their hotel Candy sneaks into Paul’s room to check his passport to see if his alibi that he was in France holds up. She finds the snorkel in the wardrobe but doesn’t think anything of it.
Paul comes in a catches her with the passport. He shows her the time it was stamped proving he was in France at the time of Madge’s death. Candy goes back to her room leaving Toto behind. The dog keeps getting the snorkel out and dropping it at Paul’s feet. He’s had enough of that and gives Toto some pills. and sends him on his way back to Candy’s room. It’s not long before Toto expires. Candy is certain Paul killed him.
Candy confronts Paul but gets nowhere. Jean, the police..no one believes Candy. She goes into Nancy Drew mode. Candy, Jean and Paul go to the beach. Candy sees a man putting on a snorkel. She’s putting it together. She looks at Paul. She looks at her. They know. Jean still thinks Candy needs to see a doctor.
The movie comes to a great ending and is well worth seeking out.