The rest agreed. Guns were not an option underground, where the firing of one bullet in such an enclosed space would put the whole crew in danger of carbon monoxide poisoning. Not even Mole, with all his big talk about what he’d do to the enemy should they ever come face-to-face, liked the idea of hand-to-hand combat in a dark space with barely enough room to swing a pick, much less a punch. They worked in tense silence, widening the distance between them and the sound of the Germans closing in on their position. After a couple of days, the scratch of enemy picks and the scrape of enemy shovels grew fainter. When Bats felt they’d evaded danger, they turned their tunnel forward again toward the enemy trenches.

After a week of digging, Bagger signaled them to stop. They were below enemy lines. He motioned for Mole to start widening the end of the gallery to carve out a chamber that, when finished, would be packed with explosives, creating a time bomb buried deep beneath the feet of the unsuspecting German soldiers huddled in their trenches.

While Bats listened for the enemy, Mole and Bagger worked the tunnel face, and Boomer and the boys removed bags of spoil and placed timber beams. Focusing on the top corners of the face, Mole kicked the spade into the clay and pressed down with his feet to work the clay free. As he pulled back, sand and water gushed from the narrow cut.

He scrambled up from his board. Everyone stopped their work and watched as Mole and Bagger rushed to plug the hole with the slab of clay they’d just removed, but wet sand continued to seep in around the edges of the cut.

Frederick dropped the beam he and George were carrying and stepped back as a growing puddle of water crept toward his stockinged feet.

In sharp, urgent hand gestures, Bagger signaled for Thomas and Charlie to bring him the full sandbag they’d been carrying to the shaft ladder.

Thomas and Charlie rushed forward with the bag, which Mole tore open. The kicker shoved two slabs of spoil into the boys’ hands. “Plug the holes,” he whispered.

The boys obeyed without question, frantically pressing chunks of clay into the widening cracks outlining the cut, but water and sand continued to leak from the tunnel face.

George and Frederick sprinted to the shaft to retrieve more bags to help. Hoisting two full bags of spoil they’d left by the ladder onto their shoulders, they hurried back, splashing through the rising water that was cresting above their ankles. They squeezed in beside Charlie and Thomas, dropped the bags at the tunnel face, and started packing the hole. Poppy chirped and flapped in her cage on the floor. Gently stroking the agitated canary’s head, Charlie lifted her cage from the water and hung it from an exposed nail on the shaft’s entrance before returning to help the other boys.

“It’s not working,” George whispered, as a jet of water sprayed out from the hole.