A complex love story in the setting of a summer holiday in the beautiful islands off the coast of Puglia (Italy). Here we find two couples: an irregular but happy Italian youth pair and the other Swedish, more mature and legal. Gunnar Lindmark is a professor of psychology, while his wife Meret find here a reminiscent of an old extramarital love, ceased because of her lover's death. This crisis triggers jealousy of the professor who kills the Italian guy.