Giovanni is a child, he must be 6 or 7 years of age. He wanders through the Tuscan countryside and speaks a weird sort of language that noone can understand. Doctors believe Giovanni's speech is the consequence of a trauma he probably experienced, and decide to 're-educate him'.
The only persons who really try to understand Giovanni are a psychologist and a nurse: the former through science, and the latter through her own instinct. They even try to learn Giovanni's peculiar language. In the hospital, the two women's efforts are not appreciated and they eventually find themselves forced to kidnap the child.
They take him to Volterra, where Marina has a house. In Marina and Elena attentive care, Giovanni begins to follow his own inclinations spontaneously: his passion for colours, his gestures, the need of physical contact are all means through which he tries to communicate. Marina, helped by her fiance who is a cellist, manages to unveil the mystery - she will find the solution in music - and will decode Giovanni's language.
The psychologist, chased by the police and trying to beat time, will finally reconstruct Giovanni's dramatic past, will meet his mother and will go to the house from which the boy escaped...