Spring of 1943: In the darkest hour of the war for the Allied Intelligence, a new and disturbing menace appears - a saboteur among the factory workers. Bomb Girl Gladys Witham (Balfour), is covertly recruited to find the traitor on the new line. She must spy on her best friends, co-workers and fellow agents, calling into question everyone and everything she has come to trust. (thetvdb.com)