A tycoon's restless wife seduces her stepson.

Phaedra, the second wife of Thanos Kyrilis, a powerful Greek shipowner, is persuaded by her husband to go to London and urge Alexis, his 24-year-old son by a previous marriage, to return to Greece for the summer. Immediately attracted to each other, the young man and the older woman become involved in a passionate love affair in Paris. When they return to Thanos' home on the Aegean island of Hydra, Alexis is racked with guilt. Thanos, delighted to have his son back, makes plans for him to enter the family business and marry the daughter of another shipbuilding tycoon with whom he is planning to merge. The jealous Phaedra, determined not to give up Alexis, confronts Thanos and tells him that she has been unfaithful with his son. In a rage, Thanos denounces his wife and mercilessly beats his son. As Alexis is about to leave, Phaedra asks him to take her with him, but he refuses and drives his car off a seacliff road. Phaedra goes to her room and swallows a lethal dose of sleeping pills, leaving Thanos to face the death of his son and his wife.