“Whoa, we’re now well below the lake’s water level. Must be some sort of partition between it and what’s down there. And this cavern is big, real big! Buzz has pinged it and estimates it to be about a mile long and half that wide – and that’s just above the water line.”

“Plenty of humidity,” said Abby, pointing with a pencil to the scrolling numbers.

A glowing set of bars appeared on the bottom of their screen – there was ten – eight were red, and only two green. It was a warning, and while they watched one more went to red.

“Shit, we’re gonna lose Buzz. We’re getting too far from the last signal relay buoy,” Freddie said.

“Good, it’s been boring as hell; wall to wall darkness,” Greg added. “Hey, Freddie, what happens if we do lose contact with the drone?”

“We’ll either just drop out of the sky, or Buzz flies away by himself.” Freddie laughed. “He’ll be free from us clumsy humans to sail away into the wild black yonder of a brave new world.”

“Thank you, Freddie, very dramatic. But how much time have we got left?” Cate frowned at the screen.

“Time? I’m guessing another few more minutes, and then it’s bye bye Buzz.” Freddie sounded like he blew more air on his fingers. “We’ll probably lose rotor and navigation control first, because it feeds off the strongest signal. But we’ll have some of the sensor and analytics for a little longer.”

“What about our eyes – the HERO4 GoPro camera has a separate signal, doesn’t it?” Abby asked. “Will that continue to function?”

“Yeah, good question, Abby. As it’s got its own WiFi frequency and battery, maybe that might still record and transmit, after everything else is gone. We’ll find out real soon, won’t we?”

The drone continued to drop, its level at eight hundred and fifty feet when the screen began to fizz with snow.

“Okay, I’m losing him. Going to switch over the HEROs frequency and try and lock the controls so it simply continues to drop without sailing off into a rock wall or something. Here goes…”

The screen went from static filled darkness, to complete dead black and there was nothing but the sound of Freddie breathing. Then suddenly the drone’s small halogens came back on, lighting nothing but walls of dark. Half the data readouts on Cate’s screen had vanished, with just chemical analysis, sonar and the camera still working.

“Worked, but we’ve lost thermal, sound and navigation. At least we can see, taste our environment, and also work out how big it is. But I’ve got no idea how fast we’re dropping or where we are at the moment. We’ve got visual markers only from now on… that’s if we get any at all.”