The Fieri family, of which Sesto is the youngest son, leads a dystopian, reclusive existence in an isolated mountain cottage. The three children, two of whom are mentally disabled and one, our protagonist, in a wheelchair, are succumbing to the idiosyncrasies of two apprehensive and sadistic parents, devoured by the germ of madness. Forced to live like a caged animal, constantly punished or rewarded for his attitude and thus forcibly domesticated, Sextus has always sought an escape through the eyes of his physical therapist, his only "contact" with the outside world. One day, however, he finds in his hands the opportunity to end that life in captivity and decides to become a "free animal" by any means at his disposal.