Penrod Schofield, who has a reputation as a troublemaker, is the president of the American Boys' Protective Association, which meets each week to report the wrongs inflicted by parents, unkind neighbors, and thoughtless policemen. During a hectic summer Penrod breaks up an amateur theatrical production and scandalizes a dancing class by his antics during a cotillion. Rupe Collins, the town tough boy, bullies the gang until he runs afoul of Herman and Verman, two colored children who get rid of Rupe with the use of scythes and lawnmowers in a hair-raising manner. The ire of leading citizens is aroused by the gang's mischief, but when the boys capture two notorious bandits, the threats turn into praise and Penrod becomes the hero of his adored Marjorie Jones.