In the story, the division of property after a man's death leaves his youngest son with nothing but the family cat. The cat, however, turns out to be intelligent and resourceful, and (in return for a new pair of boots) arranges for the boy to become a wealthy lord (the Marquis de Carabas) and marry the daughter of the king.
There is a well-known scene in the story in which the cat destroys an ogre (in order to obtain the ogre's castle as a home for the newly-made Marquis) by convincing the ogre to transform itself into a mouse, which the cat then eats.