Foyle is now working in a different new role working for British Secret Intelligence. As the iron curtain falls across Europe, MI5 believe that British atomic research has been infiltrated, and ask Foyle to investigate whether a Russian spy network could be at work in London.

Foyle investigates the death of a Russian and it ends up leading to a mysterious military facility run by a Colonel with an impeccable war record.

Foyle finds himself being drawn into the strange murder of an ex-Nazi defector and leading expert on Soviet intelligence who had been working for MI5. Sam’s husband, Adam, is pre-occupied with his new political jobleaving her concerned that she’ll be able to share some huge news with him.

Foyle, now working for British Intelligence, is drawn into the world of corrupt Nazi businessmen when a London university professor is found murdered.

Tasked with ensuring security at a high level Palestinian conference, with signs that a plot to bomb the conference maybe under way, Foyle faces a race against time to uncover not only the truth, but where the truth lies. Meanwhile Sam is determined to help a young boy in Adam’s constituency when she realises his life may be in danger because he cannot afford hospital care.

When his colleague Hilda Pierce is nearly killed in an attempted assassination, Foyle must re-examine her top secret role during the war to find out if there was a traitor at the heart of the Special Operations Executive.