While attending Professor Whippem's School for Boys. Dick Denby writes home, asking his mother to send him a suit of clothes. Mother sends her daughter Lillian to the school with the clothes, but on her arrival she is told plainly that girls are not admitted. She angrily determines to see her brother, despite the rule, goes to a hotel, puts on the suit and thus disguised, she gains admittance to the school. Dick is out playing baseball, and by mistake, she gets into a room belonging to George Burton, one of the young teachers. She starts out again to look for Dick, leaving her own clothes on the bed. Tom, a small boy, sees the girl's clothes, and as a joke, dresses up in them. He is seen and runs into Professor Whippem's rooms to hide. That gentleman's wife catches a glimpse of him, and after finding a petticoat Tom had dropped, accuses her husband of harboring a girl. Meanwhile Lillian meets Dick, goes to his room and discover her clothes are in somebody else's rooms. Dick's friends come noisily in from the ball-field, causing further complications. The Professor catches Tom, learns the lady's attire was found in Burton's room and the teacher is ordered to leave the school at once. At Dick's suggestion, Lillian puts on her own clothes, tells Burton the truth and then goes to Whippem's room to plead for him. There she is discovered by the professor's wife, and an awful row follows. Dick and Barton are called in and after explanations, Burton is reinstated and everything cleared up. Lillian returns home, where Burton is a regular caller. Wedding invitations have been issued and we can guess the rest.