The events in the concluding book of the Gentleman trilogy take place after World War II. Former spies, Philip and Monica Carlisle are on holiday in Argentina. They are outraged to discover that Heinz Kepplemann, a fugitive Nazi war criminal has escaped to South America. The couple are determined to bring the Hangman of the Rhone Valley to justice. The American couple find themselves in a web of deceit, espionage, and betrayal in the murky atmosphere of the Cold War.