In this sequel to the adventures of Coot Club, trouble is brewing for Joe, Bill, and Pete, the three boatbuilders' sons who (more or less) live full-time aboard the Death and Glory and the three Coots, Tom, Dorothea and Dick. The problem seems to be that boats are constantly being set adrift, and all the evidence points squarely at the three Death and Glories. In a clever bit of detective work, and with some help from a sophisticated photographic trap, the Big Six manage to exonerate themselves and catch the villains.