Beyond the Edge of Light by Jamie Lowther-Pinkerton

Munich, 1938. As dark shadows gather at the fringe of the traditional Oktoberfest revelry, Julia Ormesby finds herself falling in love with Conrad von Echlau. Later, on the eve of war, they are forced to recognise that the weight of history leaves them little chance of a life together. Julia moves from rescuing refugees to a pivotal role at Bletchley Park, while Conrad is awarded the Knight's Cross for the capture of a crucial Allied stronghold on the Belgian border. When he is selected for a top secret mission on the Suffolk coast, their destinies collide once more. Immediately after Dunkirk, the nation is gripped by the fear of enemy invasion - so Churchill's intelligence chiefs have decreed that every member of von Echlau's incoming unit must die.