Butch recruits Tom to join the League of Cats, a secret organization of cats who work together to catch mice after watching several of Tom's failed attempts to catch Jerry. However despite the cats' teamwork, they still fail in catching Jerry. Meanwhile, Jerry establishes a similar a secret organization of mice known as the League of Mice to get back at the League of Cats. A fight between both organizations ensue in a dark alleyway at night, with the result that the League of Cats losing the battle due to League of Mice consisting of more members (in the form of mice) than the League of Cats. The cartoon ends with the cats having to work as slaves for the League of Mice.
- The song the mice were singing is similar to "What Do We Care?" from Tom and Jerry: The Movie.
- The League of Cats members are Tom, Butch, Topsy, and Lightning. This could be a reference to the 1950's Tom and Jerry short, Saturday Evening Puss, as they go after Jerry in a group like in this episode.