January 1940. Esther Hart mourns the loss of her children in her diary. They have been evacuated out of London. Franz Niedermayer has fled Austria and is desperate to bring his wife and daughter to safety. Maurice Hickey has joined the army having been rejected by his girlfriend. Franco is a waiter at the Savoy and prays that Italy won't join the war against England, and 'Links' Reinhardt, who has been in the country for forty years, dreads the thought of being interned again. Otto Busch is a young seaman and Nazi sympathiser who, along with the rest of his crew, has been interned. As Hitler's armies sweep across western Europe there is a growing fear that in sheltering so many German refugees, the country is harbouring unknown numbers of Hitler's spies and sympathisers. As spring turns to summer and the danger of a German invasion becomes ever more imminent, the lives of the characters gradually begin to converge. As Britain stands alone, Churchill and his government has to make a decision about what to do about 'the aliens" and about who might be the enemy within. The decision made changes all their lives forever.