Duchess, the mother cat, and her kittens Berlioz, Marie, and Toulouse live a privileged life with wealthy Madame Bonfamille. However, when Madame's butler, Edgar, overhears her telling her lawyer that in her will she will leave everything to Edgar after the cats are taken care of for life, Edgar decides to do the cats in. Edgar kidnaps the cats thinking he'll drown them in the river. However, intimidated by two dogs, he drops the basket on the riverbank instead. When Madame realizes the cats are gone, the resident mouse, Roquefort, goes out searching for them. The cats, meanwhile, find themselves out in a world they never knew. Luckily, they are befriended by Thomas O'Malley the alley cat who helps them get back home. When they arrive, Edgar puts them in a sack and puts the sack in a trunk. Roquefort calls Thomas for more help. Thomas and his alley cat friends foil Edgar's plots.