While on a sailing holiday in the North Sea, two young Englishmen encounter suspicious German naval activity off the coast of the Frisian Islands—a discovery that leads them into a world of suspense and intrigue. Initially published in 1903, this thrilling adventure is regarded by many critics as one of the best spy novels ever written, notable for its richness of technical detail about inshore sailing and unsurpassed narrative style. Introduction by Norman Donaldson. 4 maps.