Though war rages across mainland Europe and London is strafed by German aircraft, the little village of Pipley in Hertfordshire bustles along much as it always has. Adrift since her best friend, George, joined the Royal Air Force, 22-year-old Olive Bright fills her days by helping at her father's veterinary practice and tending to her beloved racing pigeons. Desperate to do her bit, Olive hopes that the National Pigeon Service will enlist Bright Lofts' expertise and use their highly trained birds to deliver critical, coded messages for His Majesty's Forces.

The strangers who arrive in Pipley are not from the NPS. Instead, Jameson Aldridge and his associate are tied to a covert British intelligence organization known as Baker Street. If Olive wants her pigeons to help the war effort, she must do so in complete secrecy. Tired of living vicariously through the characters of her beloved Agatha Christie novels, Olive readily agrees. But in the midst of her subterfuge, the village of Pipley is dealing with another mystery. Local busybody Miss Husselbee is found dead outside Olive's pigeon loft. Is the murder tied to Olive's new assignment? Or did Miss Husselbee finally succeed in ferreting out a secret shameful enough to kill for?