Rhubarb the cat is the owner of the Brooklyn professional baseball team. He and his guardians, Eric and Polly Yaeger, are in Florida for spring training. A conceited ball player, jealous of Rhubarb's celebrity status, feeds info to opposing managers so the Brooklyn team will lose its Grapefruit League games.; Eric and Polly take Rhubarb to the circus, where the cat becomes part of the show. That night the cat returns to the circus and is taken captive by an unscrupulous animal trainer, who gets a hypnotist to make Rhubarb think he's a dog.