When Susie's overactive imagination begins to function, her friend Tom, despite his sound judgment, gets carried away. Convinced that Tom's parents are in desperate financial circumstances, Susie convinces Tom that they must save the day. One idea leads to another until the two children hit upon the project- a flea circus. For this purpose Bimbo, a flea-infested shaggy dog is very handy. The fleas get loose and Bimbo, thanks to Susie's fertile mind, becomes known to the adult neighbors as a fierce lion who goes about devouring children. All ends well in this comical story which is strengthened by Patricia Lauber's somewhat satiric sense of what little girls are made of.