Martino's sister, Caterina, can't work anymore for health reasons and he replaces her as cleaner for dr. Guglielmo Gioia, a mental coach. While the doctor leaves, Martino pretends to be his assistant.
Back from their honeymoon, Carlo and Anna mistakenly take the wrong suitcase at the airport and find half a billion Lire in it. They decide to keep the money and buy an apartment; but ...