After a lonely marriage and staid widowhood, Violet Fairplace Lloyd jumps at the opportunity to explore the world by escorting her friend's daughter home from finishing school in Switzerland. Jakob Sutton-Curtis has a secret. By day he's a mountain-climbing tour guide for a British travel company. By night he's a spy for the British crown, who blackmailed him into espionage. But with his cover blown, Jakob's on the run. Wounded, Jakob hides inside a trunk bound for England. When Violet discovers a bleeding man in her trunk, she nearly calls the police. Until the spies chase her, too. While hiding from Prussian spies on the frantic train journey from Geneva to London, Violet learns that happiness could be found in this tour-guide-turned-spy. And Jakob realizes that the feeling he's always searched for on mountaintops might be found in Violet instead.