Disappointed that she did not have sons, the Marchioness of Castlejordan rears her three daughters, Tommy, Willie and Noel, as boys. In their home gymnasium, the girls enjoy sports, including boxing and exercising on a trapeze. In London, the girls wear feminine clothes, but Tommy, the youngest, changes to male attire and knocks down a cockney youth in a music hall. Pursued by a crowd, Tommy jumps into the auto of aviator Lord Litterly, who admires Tommy's pluck. After she faints, Litterly takes Tommy to his rooms, where she awakens and flees through a window. Litterly is pleased to discover that Tommy is female and a relative. He follows her home and rescues her from a runaway horse. Meanwhile, Tommy's sisters have arranged a rendezvous in the gym with two beaus they met at a London ball. When the sisters' maid is warmly greeted by Litterly in the gym, Tommy crawls onto the skylight to spy. After she falls through, Tommy learns that the maid is the daughter of Litterly's childhood nurse to whom he brought news about her ill mother. At the end, the Marchioness gives her blessing for a triple wedding.