A young cat named Vincent teams up with a little mouse named Maurice in an attempt to escape a flood in an old piano. A group of sailors collects the instrument and deliver it to the museum. Here, Vincent meets an elite squad of cats who have been protecting masterpieces from rodents and other vermin for years. Vincent dreams of finding a real family of cats, but he doesn't want to lose his friend Maurice, who saved his life, so he is forced to hide him. But his friend has a weakness: gnawing on the most famous masterpieces. Everything gets complicated when one of the best paintings in the world, La Gioconda, is taken to the museum: the dream of all the mice and rats is to chew it. However, neither Vincent nor Maurice nor the Hermitage cats know that someone intends to steal it, and now Vincent must muster his courage and ingenuity to save Da Vinci's masterpiece, protect the museum's reputation, and win the heart of Cleopatra, a beautiful Egyptian chamber cat.