Once again Brenda and Derek Partridge solve a mystery in their seaport town of Winsham, England. In helping to uncover the villain's identity, Brenda and the inhabitants of Winsham discover that, like anywhere else, their neighboring reform school for boys houses both good and bad people. The town is quick to blame Bags and Barmy for the disappearance of some equipment, but Brenda and Derek's friendship with the boys leads them to other suspects. A fire in Mr. Draper's machine shop reveals the criminal collaboration of Peter Dykes, one of the reform school boys, and Charles Too-good, a ""reputable"" businessman. Bags and Barmy are vindicated as all the facts emerge. Captain Knight successfully imparts the thrill of sailing, (Brenda and Derek's favorite sport), and the flavor of English dialects. His story is fairly exciting although the psychological elements included are not altogether sound.