The owner of a building tyrannizes his immigrant tenants. Transformed into a dog by an old woman's curse, he experiences all the hardships of his situation; when a child's affection turns him back into a man, his soul is radically changed.

Alvaro is been in jail and so he consider himself the most fit to lead his three friends Mario, Otello and Spartaco. The four young men decide to start a business. They need only a van to start a transport company. But they lack the money. How can they get it?

During a police raid at Villa Borghese, the agent, a widower named Antonio Caccavallo, stays to get better acquainted with the young Carolina.