Our first real chance arrived when a cacophony of noise blew up further down the tunnel. We all straightened, looking past the guards into the lantern light flickering against the tunnel walls. The guards turned, and one of them set out to investigate. Voices rose up in angry shouts. More gunshots bounced through the cavern. I looked to Aislin and Billie, relieved to find their faces illuminated with hope.

“That’s Gavin!” said Aislin, standing up.

“Hey!” snapped the remaining guard, ...