It's 1946 and Jack and Evie are now retired. They did a bit of espionage during World War II but have decided it's now the easy life for them. The only problem is that they are now quite bored so they jump at the chance to deliver a precious gem which the UK government is returning to China. Evie's brother Jonathan is now running a nightclub in Shanghai and they are surprised to also find their son Alex who is supposed to be at university but has on an archaeological dig with an old friend, Professor Roger Wilson.