This romantic story turns on a stirring infatuation that takes hold of three young people under the influence of Simon, a Prague student. After the study year, 18 year-old Julio returns to his parental home, a little chateau on the Otava river. There he converges with his childhood friend Petr and the young boatman's daughter Klárka. Sharing her beguilement with Simon, who has quickly turned a tranquil summer atmosphere into a relationship drama, is Julio's cousin Rosa.

Trnka’s sci-fi vision of the future in which machines and robots try to substitute themselves into the most beautiful human relationships. A cybernetic robot is supposed to substitute for the loving grandmother of a little girl. The wise grandmother, however, comes back and the girl finds the warmth of her grandmother’s loving arms again. Trnka’s artistic ideas in this film can be described as both poetically fragile and dramatically cautionary.