A principal at an industrial school adds a reformatory element and applies naval discipline to a group of unruly youths, seeking to make them more tractable. The narrative follows classroom and workshop instruction in ship rigs, spars, sails, and rigging as pupils organize a crew to outfit and trial a schooner called the Lily. Alongside nautical lessons are episodic incidents—rivalries, a mutiny, disciplinary measures, outings, and a brisk trial sail on the lake—that test leadership, character, and the school's methods, ultimately depicting the boys' gradual transformation under structured labor and maritime training.