To save her kingdom, a determined young mermaid princess and her friends must join forces with the creatures that scare them the most — humans.

Love, business, anxieties, friendships, feuds, and resentments paint the picture of the main story, that of a group of criminals who for nearly fifteen years, from 1977 to 1992, cherished an illusion: that of conquering Rome. The Lebanese, Freddo, Dandi, Patrizia, and Commissioner Scialoja are some of the characters inspired by the true story of the Magliana gang. As stated by Aldo Grasso, the first season of the series gives more space to the crime scene, that is, the criminal exploits of the Magliana gang, while the second season delves deeper into the "behind the scenes" of the crime: thus, the gang's repositioning after a key plot event, and the effects and questions this has provoked in the protagonists' consciences.

Pee is a cute little worker bear. Pupù, on the other hand, is a greedy and chubby little bird while Rosmarina is an affectionate bunny. The three little heroes find themselves having to look for the perpetrator of a theft of musical scores. To identify the culprit, they will have to deal with some great operas, transforming them into tasty and brilliant parodies.

The body of a young hooker is found one night in the center of Rome, killed with a single gunshot. By questioning the pimp who exploited the young woman, and the former prostitute who was the woman's best friend, two police officers will solve the mystery.