Authur Davies is young, enthusiastic, and a brave and skilful sailor, who takes great delight in sailing his yachat Dulcibella through these difficult and dangerous waters. He asks his friend Carruthers to come out from London and join him for a sailing holiday, but his reasons for doing this only become clear to Carruthers after several days on board. It seems there is a riddle to solve, and a little mystery about a man called Dollmann. The two friends begn to investigate—and the commander of a German gunboat begins to take a close interest in them...

The Riddle of the Sands is a 1903 novel by Erskine Childers. The book, which enjoyed immense popularity in the years before World War I, is an early example of the espionage novel and was extremely influential in the genre of spy fiction. Carruthers, a minor official in the Foreign Office, is contacted by an acquaintance, Davies, asking him to join in a yachting holiday in the Baltic Sea. Carruthers agrees and he arrives to find that Davies suspects that the Germans are undertaking something sinister in the German Frisian islands...

Erskine Childers (25 June 1870 – 24 November 1922) was a British soldier, journalist, politician, novelist and writer, whose works included the influential novel The Riddle of the Sands, and a Fenian revolutionary who smuggled guns to Ireland in his sailing yacht Asgard. He was executed by the authorities of the nascent Irish Free State during the Irish Civil War.