Susan attached the canister to the pigeon’s leg, caressed its wings, and gently slid the bird into the cardboard tube. She felt the weight of the pigeon sink to the bottom. Sealing on the cap, perforated with holes to allow in air, she placed the tube with the others in the corner of the loft. She stacked them in a pyramid, careful not to rotate the pigeons upside down, realizing that in a few hours the military would load them onto planes like airmail.

She lifted a parachute and rubbed the silky material between her fingers. The parachute appeared to be terribly small, more suitable for floating a child’s toy soldier from a second-story window than dropping a pigeon from a plane. Also, the cardboard tubes looked flimsy in comparison to the former RAF baskets. She understood the reasons why the military had made the changes. Smaller packages equals fewer planes equals fewer dead pilots. But she loathed them anyway. The tubes were far too dark and restrictive, not to mention coffin-like. No way to treat a pigeon, especially one that was risking its life to save Britain. She dropped the parachute and continued loading. And with each pigeon she removed from its cubby, anxiety swelled inside her chest.

She started preparing the last of the pigeons for the mission before dawn, waking well before Bertie. He’d barely slept last night—or the past several days, for that matter—kept awake by his rounds of coughing. The only times she didn’t hear him wheezing or blowing his nose, it seemed, was during deafening bursts of antiaircraft fire.

Grandfather was right, she thought. There was likely nothing wrong with his heart. Just his dodgy knees and an ordinary cold that had progressed to the brink of pneumonia, given the rattle in his chest. Still, Dr. Collins had insisted that Bertie remain on nitroglycerin, as well as begin taking sulfa pills. But the medication, and hours spent with his head draped in a towel over a steaming pot of water, had done little to loosen his congestion.

“There’s no room at St. Margaret’s. The beds are filled with casualties from London,” Dr. Collins had said. “He’ll receive better care at home.” But the infection continued to grow in his chest. Armed with nothing more than sulfa pills, measly rations, weak tea, and old eucalyptus oil that had lost its scent, she questioned if her ministrations had done him any good.

Susan placed the last pigeon into a canister, sealed the cap, and carefully placed it on the stack. Her mind raced. Her body ached with doubt. To reassure herself, if only for a moment, she reached into her coat and removed Ollie’s recent decoded message. And read it for the fourth time.

She glanced at the stack of dropping tubes. The loft, once filled with cooing pigeons, was silent, except for the muted scratching of talons on cardboard.