"Jump now."

> Have you seen the size of this thing? Trust me, you don't want to piss it off.

"Jump now."

> This isn't doing my engines any good.

"Jump."

The ship gave the mechanical equivalent of a sigh.

> You're the boss.

Manoeuvring jets fired. The ship's nose moved, seeking its destination. It shook itself.

And jumped.

CHAPTER SEVENTEEN.

THE GLASS ELEVATOR.

Through the transparent crystal wall of the Dho Ark's debarkation lounge, Toby Drake watched the blunt triangle of the Ameline fall away into the night. Sensor pods blistered her nose. Red and green navigation lights winked along her length. He felt a strange tearing sensation, and tightened his grip on the handle of his suitcase. Even though it had been his home for only a day and a night, the old ship represented the last direct link to his former life on Tiers Cross. He watched it dwindle until it jumped away, collapsing to nothing in a flash of white light.

"Goodbye, Kat," he whispered.

Beside him, Francis Hind cleared his throat. The middle-aged Acolyte had his black cowl pushed back, revealing his thin grey hair and pale, sky-blue eyes.

"Are you ready?"

Toby nodded. He turned away from the view, hefted his suitcase, and followed Hind into a tunnel leading deep into the rock of the hollowed-out planetoid. Their footfalls echoed as they walked, and the air smelled of chlorine. Toby sniffed. It reminded him of a swimming pool.

At the end of the corridor, they passed through an airlock with reinforced ceramic doors a foot thick. It took a few seconds to cycle. On the other side, dim overhead lights bathed the corridor in a bloody sunset red. Two figures waited in the gloom. One was human, the other...

Toby recoiled. The suitcase slipped from his grasp and thumped onto the deck.

The other figure was monstrous, towering over him. Its black robe bulged in all the wrong places, and it had four twisted horns of yellowing bone where its head should be.

He swallowed. He could hear his heart hammering in his chest.

"Jesus."

Although Toby had known roughly what to expect, it was still a shock to suddenly confront one of the creatures. Every fibre of his being shrank from it. His fists clenched. In the hundred years since the discovery of the Ark, few people had come face-to-face with one. The aliens were notoriously reclusive, never venturing far from the security of the Ark, preferring to interact through their human recruits, the Acolytes.

He took another step back and felt Francis Hind's hand on his arm.

"This is one of our hosts," the older man said. "And, of course, you know Professor Harris."

With an effort, Toby dragged his eyes from the alien to the man standing beside it. Despite a few grey hairs, Professor Harris looked much as Toby remembered him. The man had his hands in the pockets of the same threadbare tweed jacket he'd worn when lecturing at the university on Tiers Cross. He still sported the same disreputable beard and his green eyes still glared from beneath a pair of untameable brows.

"Drake. Good to see you, boy. Glad you could make it."

He thrust out a hand. After a moment, Toby stepped through the airlock and shook it.

"G-good to see you too, Professor."

Toby looked sideways at the Dho. Three glistening alien eyes gazed back at him from sockets set deep in the bone at the root of the creature's horns. They looked like olives. The front horns were short and spiky, like tusks. The ones behind were almost a foot in length, curving forward from thick bases, ending in jagged and misshapen tips. It looked like a horned beetle, but how much of that was helmet and how much living tissue? Was it even possible to make a distinction?

Toby closed his eyes and dipped his head in a formal bow.

"Pleased to meet you," he said.

The Dho shivered. A series of dry clicks and scrapes came from beneath its cloak.

Francis Hind folded his hands.

"Our host is likewise honoured to make your acquaintance, Mister Drake. But right now, it's time for Professor Harris to show you the reason for your invitation."

"Yes, come along, Drake."

The Professor turned on his heel and set off down the dim red corridor, beard jutted purposefully in front of him, hands clasped firmly behind his back.

Toby hesitated.

"You go ahead," Hind said. He looked at the Dho. "I've been away from here for fourteen years. I have a lot to catch up on. You go with the Professor and I'll bring your luggage along later."

The corridor took them deeper into the rock of the planetoid. They passed service tunnels and strangely arched doorways built to accommodate the horns of the Ark's inhabitants. Dense, intricate murals covered every surface.

"The Dho carry their history with them," the Professor said. "Apparently, these hieroglyphics depict events from their past. Take this one, for instance." He stopped and pointed to a scene carved into the rock above an archway. "This is a stylised rendering of the Ark itself, and we think these specks here are smaller ships in its wake."

"And that?" Toby pointed to what appeared to be a dark and angry, looming cloud, seemingly reaching out tendrils to catch the flotilla of ships.

The Professor shook his head. "We have no idea. But these lines here appear to represent bolts of energy leaping from the smaller ships, holding the cloud at bay while the Ark makes its escape."

He straightened up.

"The Acolytes tell us this is a key scene. They call it 'The Burning Sky.' The whole ship's covered in similar pictures, but they don't appear to be arranged in any comprehensible order or sequence. As far as we can tell, they're all placed randomly. We're having terrible trouble fitting them into anything resembling a coherent chronology. It's frustrating, to say the least."

He sniffed. "Of course, our hosts insist the whole thing makes perfect sense to them, but instead of sharing their insight, they're making us work it all out for ourselves."

They arrived at an elevator. The car was two metres tall and around ten metres square, and its walls were made of the same diamond as the skin of the Ark. Harris ushered Toby inside and the doors hissed shut behind them.

"This will take us where we need to go." The Professor grinned through his beard. "However, I should warn you, you may find the ride a tad unsettling."

Toby raised an eyebrow but before he had a chance to respond verbally, the elevator leaped forward and accelerated into a dark tunnel. Instinctively, he reached out to steady himself, but there was no feeling of movement. Beyond the car's crystal walls, the lights in the tunnel zipped past, faster and faster, but inside, all was still. It was as if they were standing in a movie theatre watching pictures on a screen.

He was just getting used to the sensation when the elevator burst out of the tunnel into daylight. He twisted his head around in surprise. Behind them, a vast cliff receded, dotted with lights and openings. They were travelling through a cloudless sky with no visible means of support, and Toby's stomach twisted as he looked down at the miles and miles of empty air beneath the car's transparent floor.

"Whoa."

He looked across at the Professor, standing unconcerned in the centre of the car, hands still in the pockets of his tweed jacket.

"This is one of the caverns," the old man said. "There are hundreds of them in the Ark's interior, of all shapes and sizes. This one's a cylinder about a hundred miles in length and fifty across, with a city on its inner edge. Others house jungles or swamps. We think each one preserves a different environment from our host's home planet."

Ahead, another cliff rushed at them. Toby swallowed. He felt like a bug facing an approaching windshield.

Then they were in another tunnel. Lights whipped past the walls so fast they were little more than blurred streaks.

"Did you have a good journey from Tiers Cross?" Harris asked.

Toby closed his eyes. Without visual cues, it was impossible to tell whether or not they were moving.

"Yes, I suppose so."

He thought of Katherine Abdulov lying warm and tousled in his arms and felt another stab of loss and longing.

"Good, good. And I trust you brought your research with you?"

"Yes sir. I've got electronic copies of everything ever written on the Gnarl, including all my own papers and notes."

"And some books, judging by your suitcase?"

Toby opened his eyes with a smile. "A habit I picked up from you, Professor."

Harris twitched his moustache. "Quite. Well, you're going to need them. Your notes, I mean."

Toby frowned. "Can I ask why? Only I've come all this way, and no-one's told me anything."

The lights outside the car were passing more slowly now: they were decelerating.

"No need, you'll be able to see for yourself in a moment." The Professor gestured forwards. Ahead, a circle of light lay at the end of the tunnel, growing as they slowed. By the time they reached the tunnel's end, they were travelling at walking pace.

"Behold!" boomed Harris, flinging his arm theatrically. "Behold the reason I asked you here."

Toby walked forward and placed his hands on the transparent wall. They had emerged into another cylindrical chamber, this one maybe a kilometre in diameter and twice that in length. The walls were blank and smooth. Ahead, the air at the centre of the empty space had been curdled. There were clouds twisted into unlikely spirals, and at the centre, flickering with blue static discharge, something writhed. It looked like a ball of angry snakes. Strange symbols flickered across its surface and were lost from sight. It seemed to be drawing in all the light in the room, like a plug draining water from a sink.

In the glass elevator, Toby stepped back and shook his head.

"I don't believe it."

There couldn't be another one. Could there? In all the years he'd spent studying the Gnarl at the heart of the Bubble Belt, he'd never supposed it to be anything other than unique.

He felt Harris's heavy hand clap him on the shoulder.

"Believe it, my boy. This is the reason you were called here. You've spent your life studying one Gnarl. Now, we need your expertise with another."

Toby turned to him.

"But what's it doing here?"

The Professor's brows drew together like wary caterpillars circling each other.

"Doing here?" He chuckled. "My dear boy, how else do you think you power an Ark of this size?"

Toby shook his head. His eyes were watering but he couldn't look away. He was captivated by the ever-changing surface. It moved like oil on water.

"Power...?"

"Oh yes!" Harris rubbed his hands together. "My boy, that wonderful anomaly out there is the engine. It powers this vast, insane spaceship."

He leaned forward and tapped Toby on the chest.

"And that's where you come in, Mister Drake. We want you to tell us how it works."

CHAPTER EIGHTEEN.

FISSURE.

First came the pain. Then, after a while, Ed realised he was conscious. He didn't know what had happened to him, but time had passed, and his head hurt. He was lying on his side, and something heavy lay on his hip, pressing him down. For a chilling instant, he thought he was back on that table in Bethnal Green, with Pavle holding him down, waiting for Grigor to shatter his wrists with the flat side of a butcher's cleaver.

"You must understand that this is a matter of honour."

Cold water bubbled against the side of his face, and his eyes snapped open with a gasp. He twisted his neck, lifting his face clear. His cheek felt frozen. Flailing around in panic, his hands gripped the steering wheel, and he realised he was still in the Land Rover, which was on its side, and slowly filling with water.

The car had toppled into a rocky fissure and now lay wedged in the stream at its bottom. Just enough light came from above for him to make out its rough stone walls and the shallow, fast-moving water covering its gravelled floor. The driver's side window had shattered on impact, and his cheek had been resting on gritty kernels of broken glass. Blood mixed with stream water. Kristin lay on top of him, dead or unconscious, her head and shoulder digging into his hip, her legs wedged in the foot well on the passenger side. Neither of them had been wearing seatbelts.

Ed flexed his back. He could smell petrol. His shoulder hurt where he'd slammed against the inside of the door. His clothes were wet from the water coming in through the broken window. Carefully, he twisted around in the confined space, hampered by Kristin's weight pressing on him. He did his best to lower her gently to the floor, trying to keep her as dry as possible. She was heavier than he expected, and a red bruise discoloured the side of her right eye. She was starting to stir. Not dead, just stunned and groaning faintly, her eyelids fluttering like butterflies caught in a spider's web.

When her legs touched the icy water, she jerked in his arms.

"Ed?"

"I'm here."