In times of war, how do you know who to trust? Celia Ashton has driven ambulances throughout the Blitz for the Bloomsbury Auxiliary Ambulance Depot. Cool under fire, she revels in her exciting and extremely dangerous job. When her husband, a known Nazi supporter, is released from prison, Celia refuses to return to her unhappy marriage. Instead she joins forces with Simon Levy, a man who appears to despise her, to help a young Jewish orphan. In so doing she discovers that one ruthless traitor can be more dangerous than any German bomber, and that love can cross any boundary.