Rich eccentric T.J. Banner adopts a feral cat who becomes an affectionate pet. Then T.J. dies leaving to Rhubarb most of his money and a pro baseball team the Brooklyn Loons. When the team protests publicist Eric Yeager convinces them Rhubarb is good luck. But Eric's fiancée Polly seems to be allergic to cats and the team's success may mean new hazards for Rhubarb.