Returning to Pipley following her FANY (First Aid Nursing Yeomanry) training, Olive is eager to step up her involvement in the war effort. Her pigeons are being conscripted to aid the Belgian resistance, and it's up to Olive to choose the best birds for the mission. To protect the secrecy of their work, she must also continue the ruse of being romantically involved with her superior, Captain Jameson Aldridge, a task made more challenging by the fact that she really does have feelings for the gruff Irish intelligence officer.

But perhaps the greatest challenge of all comes when an instructor at Station XVII, the top-secret training school housed at Brickendonbury Manor, is found dead in Balls Wood by a troop of Girl Guides. The police quickly rule Lieutenant Jeremy Beckett's death an accident, but based on clues she finds at the scene, Olive begins to suspect he might have been a spy. Involving the reluctant Jamie, she is determined to solve the murder and possibly stop a threat to their intelligence efforts which could put the Belgians--not to mention her pigeons--in grave danger.