World War II comes to Farleigh Place, the ancestral home of Lord Westerham and his five daughters, when a soldier with a failed parachute falls to his death on the estate. After his uniform and possessions raise suspicions, MI5 operative and family friend Ben Cresswell is covertly tasked with determining if the man is a German spy. The assignment also offers Ben the chance to be near Lord Westerham's middle daughter, Pamela, whom he furtively loves. But Pamela has her own secret: she has taken a job at Bletchley Park, the British code-breaking facility. As Ben follows a trail of spies and traitors, which may include another member of Pamela's family, he discovers that some within the realm have an appalling, history-altering agenda. Can he, with Pamela's help, stop them before England falls?