Juan is a widowed dad with three children; he was on the verge of ruin, but he inherits a fortune from his uncle, Giancarlo; in exchange, the family will have to take care of Chueco, a chimpanzee who has a big secret: he can talk.

Chueco goes in for a check-up and the vet advises Juan to feed him special canned food for chimpanzees. But Chueco doesn't like the food and is not willing to change his usual diet which consists of eating whatever he wants. Chueco mixes the contents of the cans with Juan's food when he's not looking, but the ape food turns out to have an unexpected side effect on humans.... hair growth! At first, Juan is delighted to see his baldness disappear, but things soon begin to escalate and Juan's hair and beard start to grow completely out of control during a romantic dinner date with Sofía. Once again, Chueco spreads chaos with one of his brilliant ideas.

Chueco goes to the cinema; he becomes bored and annoys the audience until he gets kicked out.

The family is forced to treat Chueco like a chimpanzee to stop him from being taken to a sanctuary.

Chueco turns into Dr. Apeius, the manager for Los Desquiciados, Delfina's rock band.

Chueco teaches Juan the noble art of poker and deceit, but the consequences are catastrophic.