A group of adventurous boys take command of a house-boat for a cruise up the Hudson, encountering rescues, new friendships, misunderstandings, and a sequence of episodic exploits. They assist a young former tutor who joins their party, face rivalries and accidents including a collision and a struggle to retain the vessel, and encounter a variety of characters whose interventions complicate and then resolve disputes. Episodes include mechanical troubles, social encounters, sporting contests, and nocturnal rescues, and the voyage concludes with reconciliations and the successful close of the cruise.