Regarded as one of the best spy stories ever written, this is the classic Secret Service novel. More like fact than fiction, it holds a special place in the affections of spy-novel fans for its richness of technical detail about inshore sailing, its highly sympathetic characters, an unsurpassed narrative style, and a setting and plot that recapture the European political scene on the eve of World War I.

Two young Englishmen, Davies and Carruthers, head for the Baltic Sea in the late 1890s for a holiday of sailing and duck-shooting. The mood gradually darkens as Davies discloses his suspicions of espionage in the North Frisian Islands, and Carruthers joins in an investigation that develops into a series of increasingly dangerous intrigues. Norman Donaldson, an expert on detective and suspense fiction, offers an Introduction with details about the author as well as the novel's background and its place in the history of the spy-novel genre.