I charged headlong down the tunnel, taking huge strides, crashing into the walls, my only thought to get away—away—from the squeaking, flapping, fluttering mass that surrounded me, that filled my mouth and nose with a choking sour stench, and set my eyes streaming.

Bats. Only bats.

I knew Scratch was right; we’d seen bat caves in South America, vast clouds bursting out from the mountains at sunset. Of course there would be bats in the lava tubes; it was the perfect home for them. But reason couldn’t stop me running, couldn’t stop my body believing it was being chased by an army of murderous squealing demons of the dark. There were so many of them all around me. Some part of me said I should stop and just let the colony fly on past, but the rest of me was determined to run for my life. So I kept on, arms wrapped over my head, covering my ears against their piping squeals, their bodies and sharp wings brushing against my legs, arms, face, until it seemed I must have run too far, missed the light of the crack in the ceiling and the hole I had fallen through. But still I raced on, until the cloud of tiny bodies thinned out and I staggered to a stop and collapsed to the floor, arms still shielding my head. The last stragglers fluttered past and I flinched until there was finally silence and the pounding in my ears began to fade. Except it didn’t, quite. There was still pounding, but it was from outside. The sea?

I unfolded myself and found I was no longer in total darkness. The black had become gray.

I shook my head as one solitary bat squeak remained, piping like the nest of sparrows in the chimney at my aunt’s place before she got at them with a broom.

I scanned around the tunnel, goose bumps rising. Maybe the sound was lodged in my ears now, because I couldn’t see the source of it …

Movement by my feet made me start back, still jumpy. A flutter. I crouched and saw it was a lone bat, and very tiny, with a body half the size of a house mouse, covered in red-brown fur, with a flattened little face.

“Minutes ago, I’d been terrified … of you. But you’re just a helpless little scrap,” I whispered.

Well, I couldn’t just leave it there. I scooped it up and it squeaked more loudly and wriggled, then fell silent. Had I scared it to death? I shifted it to the palm of one hand. Its black wings were rumpled, and I gently spread them—there didn’t seem to be any injury. It might be a new species that only lived in these tunnels, one of the animals that made Mr. Darwin so interested in the Galapagos.

Without warning, the bat sprang from my hands, fluttered haphazardly around my head, then flew into the tunnel beyond, disappearing where the passage began to widen.