A new patient mysteriously appears in a psychiatric ward. He claims to come from another planet to study humans and their behavior. The alien is gentle but criticizes humans for their harsh treatment of each other. The assigned psychiatrist is himself unhappy, and affected by the patient's insight. But he is ordered to treat the patient according to institutional procedure.

During a period of political upheaval, three friends, later to be joined by the fourth, Pimpi, a Peronist youth activist, rent a place in Mar de Ajó for three summers to set up a disco.