Alena Marshall (Diana Rigg) is a gorgeous female star. She is a bohemian by nature and never hides her love for other men. She also enjoys the feeling of being pursued by men, thus completely ignoring the feelings of her husband and adopted daughter. Patrick (Nicholas Clay) is a handsome young man with strong blood. Although he already has a frail wife Christine (Jane Birkin), he still can't resist the temptation of Alena who secretly sends him a glance. This year, the resort hotel "Happy Roger" on the island next to Leathercombe Bay has become a stage for showing evil. All tourists who come here for vacation seem to have more or less interests with Alena. Where there is evil, there is Polo (Peter Ustinov), and this time is no exception. He is smart and sees all the contradictions. Alena is dead, which is no surprise to everyone. Although everyone has a motive for committing a crime, everyone has a perfect alibi. Who killed Alena? In fact, the murderer had already revealed his true colors.