Henry Lane is arrested and accused of spying in Amaria. Cmr. Hastings tells his wife that Henry is a Russian spy and a trial will be embarrassing. The USSR says he is British spy. Almaria decide he is too hot to handle and release him.

Almarian Anton Werner is a British spy who is getting fake letters, from his sister, needing money. Richard Cadell arranges to bring a lookalike but walks into a trap. The Americans have used him to make a swap for their agent.

The Embassy are struggling to break a new cipher. They ask for Mark Cavelet from the Hungarian Consul. Cadell's meets Victor Tridy but he doesn't want to be Calvet after 20 years of inactivity. Cadell is told to get him back or kill him.

Britain and the Soviet Union agree to exchange captured agents and use Amalia as the site of the transfer.

It is not unusual for people to visit Amalia as a tourist but when a British government mathematician visits, his trip is particularly interesting considering he is fond of gambling and deeply in debt.