Keep your allies close but keep your enemies closer . . .
Germany 1944. The Allied invasion is not far away - and the high command desperately need to know where it will take place. It is time to activate one of Hitler's last spies in Britain - Catherine Blake, a "sleeper" introduced by German intelligence before the war, awaiting her orders.
British Intelligence also has its orders - and a peacetime university professor, Alfred Vicary, has been recruited personally by Churchill to carry them out. When Catherine sets out to seduce the weakest link in the Allied defences it is up to Vicary to find her. And stop her before it is too late. But are his own people keeping something from him?