One by one their helmet torches went out. Aimee noticed that Alex hadn’t used his light for ages and couldn’t remember when he ever had it on. She saw him give some quick signals to Tank and Takeda who both pulled lenses down over their eyes; infra-red, she guessed. Seconds passed with nothing occurring and Silex started to complain in the blackness. Aimee noticed that his voice had moved as he had taken the opportunity to get a lot closer to her. Creep, she thought, as she sshhhhed him in the dark.

After a few more seconds the bioluminescent stars appeared again on the ceiling, then on the walls, and after a minute, they could actually make each other out in the cavern. They were no longer in the sightless black of the cave, but in a soft blue twilight.

“Cool,” Matt said, looking up, and to perform his own test clapped his hands just once very loudly. It came as such a surprise that even the HAWCs swung around towards him with their rifles raised. Immediately, and as he expected, all the cold lights went out, leaving them once again in the impenetrable darkness. But what no one was expecting was to hear the loud splash from the other side of the stream. Everyone switched their helmet torches back on and some lit up their handhelds for good measure.

Alex spoke to his HAWCs while never taking his eyes off the stream. “Something large entered the water about a hundred feet farther down—eyes on. Everyone else get behind us.” The stream, which had been as flat and calm as ice, suddenly lapped up on the sand.

“Surge wave, something’s coming towards us in the river. Get ready.” The group backed up and positioned themselves behind the HAWCs who had their rifles pointed at the river surface.

It happened quickly. The smooth stream surface exploded as the thing charged out of the water like a shiny, black torpedo. An enormous mouth opened to display a zigzag of deadly teeth at the front of a twenty-foot-long muscular body. It powered itself at Alex on squat legs, aiming to take him round the waist. None of the HAWCs flinched; three rifles fired at once, sending highly compressed bullet-sized projectiles of air into the long body. Holes ruptured along its head and flank and the creature thrashed and thumped heavily on the sand for a while before trying to retreat back into the stream. Tank fired one more round between its eyes and it dropped still on the shore, its flattened tail still in the water and its great shovel-shaped head falling to the sand leaking greenish fluid.

Everyone stood in silence for a few seconds until Matt spoke. “I love this place! This is like fucking Pellucidar. Do you know what this is?” he asked wide-eyed to the still panting group.

“Looks like a cross between a shark and some sort of alligator,” said Tank.