The novel is set in the fictional Central European country of Evallonia in the early 1930s. It concerns the involvement of some Scottish visitors in the overthrow of a corrupt republic and the restoration of the monarchy. It is a sequel to Castle Gay, in which some Evallonians visited Scotland on a secret mission two years before the start of this novel. At the beginning of the novel several characters formerly seen in Huntingtower and Castle Gay are about to go to Europe for the summer, for a number of different reasons: Mr McCunn going to a German Kurhaus for his health, Alison to join her parents in the Tirol, the Roylances to attend a dull conference in Geneva, Jaikie on a walking tour, Dougal on a mission for his newspaper...