Tommy Mooney-back in England after his adventures in Telegram For Mrs. Mooney-goes with his brother's fianc e to RAF Rochford, where he begins to suspect that a Nazi spy is working mischief at the base. Airmen are mysteriously wounded, Spitfires are sabotaged, someone has been poisoning the food. No one escapes Tommy's radar, especially after Daphne falls ill and is hospitalized. That night the base is attacked, setting off a chain of events...