"Emerald is the fast-moving sequel to The Dutch Caper, showing Cormack and Woodward being flown into Berlin in order to bring out ‘Emerald’, the mistress of a high-ranking member of Hitler’s staff in Berlin but also a long-standing British undercover agent. She has been passing on information from Hitler’s Berlin Bunker for several months now, but has now become the object of an intensive Gestapo search. Emerald’s real name is Marianne Kovacs, the Irish born wife of a Hungarian diplomat, who has been working for SIS for four years, but who knows that she stands little chance of survival if she remains in Berlin. (Her character is based on an actual British agent, whose fate in real life remains a mystery.) Cormack, Woodward and Marianne have to escape from a Berlin that is being systematically destroyed by the approaching Soviet Army, with the Gestapo hot on their heels. To add to their problems, the Soviet NKVD (the fore-runner of the KGB) starts to take an interest in them as well…"