The drone lowered for a moment, gently rose, and then tilted forward to show a small box on the ground with a green blinking light.

“Relay beacon 1, away. Good to go.” The drone moved on, and they heard an intake of breath from Freddie as they approached another narrowing in the cave. “Jesus, going to be tight; if we get wedged, we’re done. Cate, give me a go/no-go on this; after all, it’s your kit.”

Cate didn’t hesitate. “Go for it; that’s why were all here.” She checked the timer on the side of the image – they’d been flying for twelve minutes – so far so good. The drone eased in, the internal gyros keeping the small four-prop craft rock-steady.

“Going down now. Angle of descent is about twenty-five per cent. Cave now opening out. Thank you, oh god of the caves. Hey, guys, who was the god of the caves?”

“Lots of them,” said Abigail. “Mostly minor Greek goddesses like Nyx, Hypnos, and Eileithyia, come to mind.”

“Cool, all goddesses. I like it,” Freddie said.

“And don’t forget Hades… but he’ll be deeper where it’s nice and hot,” Greg said, turning and winking at Abby.

“Hold it. Swivel left.” Cate sat forward and then broke into a smile.

On the wall they could see an arrow and underneath, the initials ‘J.G.’. Cate exhaled with satisfaction. “This is it.”

“You said he went missing…” Greg glanced at her. “…so, um, Cate, you’ve got to be ready for what we find. He could still be in here – or what’s left of him.”

Cate stared straight ahead. “Even if he was there, it would be closure, nothing more.” She gripped the desk edge. “Whoa…”

“Well, well, well, looks like your grandfather wasn’t the only one in here; this place was a regular Central Station.” Greg straightened in his seat.

The drone illuminated the cave wall, showing ancient rock art images of small human figures, fish, sharks, turtles, and other creatures that were unidentifiable. Natives either speared them, or were themselves pulled into the water, and attacked.

“Awesome,” Abby breathed. “And old.”

“Must be Nantouk,” Greg said. “But this looks almost prehistoric. How long have they been here?”

“Around ten thousand years, but before them, who knows.” Cate’s mouth hung open in an awed smile.

The next narrow fissure took five full minutes to navigate, but this one opened to a large flat room with evidence of a recent rock fall at its edges. But that wasn’t what held their attention – at its center was a dark, gaping hole in the cave floor.

“You seeing this, Cate?” Freddie sounded breathless. “The wall, do you see?”

“Yes.” Cate had her nose only inches from the screen. “Blackened. There’s been an explosion of some sort… and fairly recent.”