Who is seen by someone's sister?
Harmon is a wealthy landlord.  When he goes to visit one of his tenements, he gets caught in the middle of a brawl between groups of kids, one of whom, Clipper Kelly starts to attack Harmon.  When Harmon defends himself, he is seen by Clipper's sister, Margie (Page).  Harmon falls in love at first sight and begins to woo her following his trial for attacking Clipper.  In order to demonstrate that he is okay, Harmon opens a gymnasium for the street boys, but Clipper, who has fallen in with a small-time gangster, Butch, wants nothing to do with Harmon and turns the other boys against him.
Harmon tries to win them over by staging a wrestling match with his friend Poggle and a rigged boxing match with Mulvaney.  In the meantime, Butch has gotten Clipper involved in a series of robberies with Clipper dressed as a woman.  When Butch and Clipper believe Harmon has learned of their activities, Butch orders Clipper to kill Harmon during a stage play that is being performed at the gymnasium, but Clipper gets cold feet.  Butch grabs Harmon, who is dressed in Clipper's drag costume, and heads up to Harmon's mansion to rob it.  Butch's gang joins them and Clipper and the other boys come to Harmon's rescue.
Harmon