It is based on "The Brave Adventures of Lapitch", a 1913 novel by Croatian author Ivana Brlić-Mažuranić. In this adaptation, all of the characters are animals, and the title character is a mouse, rather than the human character of the original work. As with the book, the film is about a shoemaker's apprentice who leaves the confines of his ill-tempered master, and sets off on an adventure. During his journey, he befriends a circus performer named Gita, and fights against the evil Dirty Rat.