A group of college friends convert a rented houseboat into the Jolly Roger and set off on a summer cruise up the river, blending boyish fun, social calls, and practical boatwork with a chain of adventures. They entertain and spar with an observant guest, face a nighttime burglary and temporary imprisonment, follow clues into a gipsy camp, and deploy clever traps and tactics to outwit suspicious figures. Episodes combine humor, resourcefulness, and friendship, culminating in reconciliations, gifts, and farewell scenes that close the seasonable voyage.