I was just as nervous sneaking around in the dark the second and third time I did it. But I learned which floorboards creaked, which stair rail rattled, how to stick to the wall so I didn’t bump into furniture. The nerves didn’t go away, but I got better at my job. I wondered if that was how the airmen felt about flying into battle.

The next message wasn’t much use—and half of it was missing.

REPEAT SPECIAL APPROACH STORM FRONT IV XII

FIRST GREEN LIGHT BEFORE HALF MOON

Jamie:

Another German submarine! Coastal Command sent us on a not-too-risky mission to blast holes in Lista, the Luftwaffe aerodrome that didn’t exist yet, as retaliation for the railway attack and to create a headache for the Nazi planners. We wouldn’t have spotted that disabled U-boat if we hadn’t known it was there, but it wasn’t even out of our way. I let Adam Stedman in Madeira do the honors of sinking it. I didn’t want to make Pimms look greedy… or to push our luck.

But our luck held, even though the incomplete message Louisa deciphered next wasn’t as straightforward.

I tossed and turned on my narrow top bunk for three hours instead of sleeping, wondering what it meant.

REPEAT SPECIAL APPROACH STORM FRONT IV XII

FIRST GREEN LIGHT BEFORE HALF MOON

St. Nicholas Day, 6 December, would be the half-moon. Christmas was coming; IV XII came before that, 4 December 1940.… And already it was past midnight on 2 December. The fourth was the day after tomorrow. What storm front was approaching on the fourth?

“Blimey, Jamie, give it a rest,” Silver hissed from the mattress below. “When you turn over you shake the whole bunk.”

“Sorry.” I lay on my back like a block. Every inch of me felt uncomfortable.

“What’s eating you?”

“Are we due some bad weather?” I asked. Silver always kept an eye on the MET conditions.

“Just the usual overcast and wind,” he told me. “Do you want an excuse to stay on the ground? ‘Lack of moral fiber, Flight Lieutenant Beaufort-Stuart!’”

I snorted. “Now? As if!”

“As a matter of fact it’s going to be quite nice for a few days, which will give the ATA a chance to deliver those new Blenheims—well, old ones without holes. New for us.” Silver’s voice dropped to a whisper. He asked almost inaudibly, “What’s really eating you?”

I leaned over the edge of the bed so my head hung closer to his, and he leaned on his elbows so his head was closer to mine, and we carried on whispering.

“I can’t figure out the last message.”

“Maybe we need to pass it to a real codebreaker,” Silver suggested.

“Yes, I thought of that, but then we’d have to tell Cromwell. Even if we went straight to Intelligence he’d find out.”