Three wealthy young women--Nancy, Nora, and Carla--bored with the normal pleasures of life--seek new thrills and decide to take Nora's father's cruiser on a weekend trip to the nearby Dalmatian coast to experiment with LSD, tape-recording the action that takes place. Nancy invites Marco, a medical student who is a total stranger, to join them. After a lazy day of swimming and skin diving, they gather in the lounge and take LSD. They then throw overboard all possibly harmful items but overlook a small pistol. When Marco comes down from his LSD trip he is bleeding internally from having been shot in the spleen and knows that he must be hospitalized immediately. Upon entering one of the cabins, he discovers Nancy, whose latent lesbianism has been brought out by the drug, in bed with Carla. He urges them to take him to the nearest port in Yugoslavia, and though they promise to do so, they become afraid of the consequences and, believing that Marco has exaggerated his condition, continue their leisurely cruise. Soon, however, Carla realizes Marco's danger and pleads with the others to allow her to go to a pharmacist in a small Yugoslavian port to get morphine. Carla obtains the drug by offering the pharmacist her virginity; but her sacrifice is in vain, for Marco dies. Nora and Nancy coldly dispose of the body and once back in the resort of Caorle go ashore as if nothing has happened. Carla, realizing she was in love with Marco, rushes to the sea and waits to be swept away by the waves.
