Millionairess actress-singer Marie Coleby (Deborah Coulls) lives in a luxurious villa on a deserted beach. One afternoon following a TV commercial shoot at the villa she incites gardener Gordon Mason (Chard Hayward) to mayhem and murder. The unexpected arrival of Marie's sister Jenny Nolan (Louise Howitt) hinders Mason's attempts to dispose of the body. He then decides to kill Jenny. But she is equally determined to stay alive ... so begins a battle of wits. Jenny's salvation seems at hand when two security men arrive at the villa, but only one, Officer Collings (Roger Ward) survives the initial siege. Then Jenny is alone to face Mason for the final time ...