The baby was wrapped in three wool blankets, but his tiny face was pale and slick with sweat.

“He’s burning up,” Sullivan said, his eyes wide with fear in the blue light.

“We have to keep moving,” I said, taking Luca back into my arms.

The weight of my son felt incredibly light, almost weightless.

I held him close, feeling the rapid, shallow rise and fall of his chest.

Above us, a heavy steel door slammed closed with a deafening metallic clang.

It was the main door to the bunker upstairs.

Then, the sound of the deadbolt sliding into place echoed down the hatch.

Giovanni had locked us in.

“He’s staying up there,” Sullivan said, looking up at the ceiling.

“He has to,” I said. “He has to stop them from reaching this hatch.”

A sudden, sharp rattle of automatic gunfire erupted directly above our heads.

The sound was muffled by the thick concrete, but it was continuous.

It sounded like a hammer striking an anvil over and over again.

Then, a low hum vibrated through the brick walls of the tunnel.