A saxophone-playing, divorced psychiatrist, Dr. Denis, is baffled by the unexplained arrival of a new patient in his mental hospital. The highly intelligent newcomer, called Rantes, has extraordinary gifts and spends long hours in the yard facing southeast, where he claims to receive communications from his home planet. He is visited by the saintly Beatriz, who works in a church, and Denis asks her questions about Rantes.

The bond between the three people begins to transgress the ordinary boundaries between doctor and patient, and culminates in an excursion to a concert in the park. Charmed by Beethoven's "Song of Joy," Rantes instigates generalized waltzing and takes over from an inexplicably obliging conductor. Back in the asylum, the other patients feel the vibrations emanating from Rantes' concert and engage in a good-humored romp. The doctor is reprimanded for the embarrassing situation, and begins to doubt the integrity of the psychiatric enterprise. A weakened Rantes dies after electroshock therapy and the film ends in ambiguity.