Cilia-of-Gold thought of denying it; but she turned away, her depression deepening. “I couldn’t expect to keep secrets from you. Do you think the others are aware?”

The hairlike cilia lining Strong-Flukes’ belly barely vibrated as she spoke. “Only Ice-Born suspects something is wrong. And if she didn’t, we’d have to tell her.” Ice-Born was the third of Cilia-of-Gold’s mates.

“I can’t afford to be weak, Strong-Flukes. Not now.”

As they swam together, Strong-Flukes flipped onto her back. Tunnel water filtered between Strong-Flukes’ carapace and her body; her cilia flickered as they plucked particles of food from the stream and popped them into the multiple mouths along her belly. “Cilia-of-Gold,” she said. “I know what’s wrong. You’re carrying a Seeker, aren’t you?”

“…Yes. How could you tell?”

“I love you,” Strong-Flukes said. “That’s how I could tell.”

The pain of Strong-Flukes’ perception was as sharp, and unexpected, as the moment when Cilia-of-Gold had first detected the signs of the infestation in herself… and had realized, with horror, that her life must inevitably end in madness, in a purposeless scrabble into the Ice over the world. “It’s still in its early stages, I think. It’s like a huge heat, inside me. And I can feel it reaching into my mind. Oh, Strong-Flukes…”

“Fight it.”

“I can’t. I—”

“You can. You must.”

The end of the tunnel was an encroaching disc of darkness; already Cilia-of-Gold could feel the inviting warmth of the Chimney-heated water on the cavern beyond.

This should have been the climax, the supreme moment of Cilia-of-Gold’s life.

The group’s old Chimney, with its fount of warm, rich water, was failing; and so they had to flee, and fight for a place in a new cavern.

That, or die.

It was Cilia-of-Gold who had found the new Chimney, as she had explored the endless network of tunnels between the Chimney caverns. Thus, it was she who must lead this war — Seeker or no Seeker.

She gathered up the fragments of her melting courage.

“You’re the best of us, Cilia-of-Gold,” Strong-Flukes said, slowing. “Don’t ever forget that.”

Cilia-of-Gold pressed her carapace against Strong-Flukes’ in silent gratitude.

Cilia-of-Gold turned and clacked her mandibles, signaling the rest of the people to halt. They did so, the adults sweeping the smaller children inside their strong carapaces.

Strong-Flukes lay flat against the floor and pushed a single eye stalk towards the mouth of the tunnel. Her caution was wise; there were species who could home in on even a single sound-pulse from an unwary eye.

After some moments of silent inspection, Strong-Flukes wriggled back along the Ice surface to Cilia-of-Gold.

She hesitated. “We’ve got problems, I think,” she said at last.

The Seeker seemed to pulse inside Cilia-of-Gold, tightening around her gut. “What problems?”

“This Chimney’s inhabited already. By Heads.”

Kevan Scholes stopped the rover a hundred yards short of the wall-mountain’s crest.

Irina Larionova, wrapped in a borrowed environment suit, could tell from the tilt of the cabin that the surface here was inclined upwards at around forty degrees — shallower than a flight of stairs. This “mountain,” heavily eroded, was really little more than a dust-clad hill, she thought.

“The wall of Chao Meng-Fu Crater,” Scholes said briskly, his radio-distorted voice tinny. “Come on. We’ll walk to the summit from here.”

“Walk?” She studied him, irritated. “Scholes, I’ve had one hour’s sleep in the last thirty-six; I’ve traveled across ninety million miles to get here, via flitters and wormhole transit links — and you’re telling me I have to walk up this damn hill?”

Scholes grinned through his face plate. He was AS-preserved at around physical-twenty-five, Larionova guessed, and he had a boyishness that grated on her. Damn it, she reminded herself, this “boy” is probably older than me.

“Trust me,” he said. “You’ll love the view. And we have to change transports anyway.”

“Why?”

“You’ll see.”

He twisted gracefully to his feet. He reached out a gloved hand to help Larionova pull herself, awkwardly, out of her seat. When she stood on the cabin’s tilted deck, her heavy boots hurt her ankles.

Scholes threw open the rover’s lock. Residual air puffed out of the cabin, crystallizing. The glow from the cabin interior was dazzling; beyond the lock, Larionova saw only darkness.

Scholes climbed out of the lock and down to the planet’s invisible surface. Larionova followed him awkwardly; it seemed a long way to the lock’s single step.

Her boots settled to the surface, crunching softly. The lock was situated between the rover’s rear wheels: the wheels were constructs of metal strips and webbing, wide and light, each wheel taller than she was.

Scholes pushed the lock closed, and Larionova was plunged into sudden darkness.

Scholes loomed before her. He was a shape cut out of blackness. “Are you okay? Your pulse is rapid.”

She could hear the rattle of her own breath, loud and immediate. “Just a little disoriented.”

“We’ve got all of a third of a gee down here, you know. You’ll get used to it. Let your eyes dark-adapt. We don’t have to hurry this.”

She looked up.

In her peripheral vision, the stars were already coming out. She looked for a bright double star, blue and white. There it was: Earth, with Luna.

And now, with a slow grandeur, the landscape revealed itself to her adjusting eyes. The plain from which the rover had climbed spread out from the foot of the crater wall-mountain. It was a complex patchwork of crowding craters, ridges and scarps — some of which must have been miles high — all revealed as a glimmering tracery in the starlight. The face of the planet seemed wrinkled, she thought, as if shrunk with age.

“These wall-mountains are over a mile high,” Scholes said. “Up here, the surface is firm enough to walk on; the regolith dust layer is only a couple of inches thick. But down on the plain the dust can be ten or fifteen yards deep. Hence the big wheels on the rover. I guess that’s what five billion years of thousand-degree temperature range does for a landscape…”

Just twenty-four hours ago, she reflected, Larionova had been stuck in a boardroom in New York, buried in one of Superet’s endless funding battles. And now this… wormhole travel was bewildering. “Lethe’s waters,” she said. “It’s so — desolate.”

Scholes gave an ironic bow. “Welcome to Mercury,” he said.

Cilia-of-Gold and Strong-Flukes peered down into the Chimney cavern.

Cilia-of-Gold had chosen the cavern well. The Chimney here was a fine young vent, a glowing crater much wider than their old, dying home. The water above the Chimney was turbulent, and richly cloudy; the cavern itself was wide and smooth-walled. Cilia-plants grew in mats around the Chimney’s base. Cutters browsed in turn on the cilia-plants, great chains of them, their tough little arms slicing steadily through the plants. Sliding through the plant mats Cilia-of-Gold could make out the supple form of a Crawler, its mindless, tubelike body wider than Cilia-of-Gold’s and more than three times as long…

And, stalking around their little forest, here came the Heads themselves, the rulers of the cavern. Cilia-of-Gold counted four, five, six of the Heads, and no doubt there were many more in the dark recesses of the cavern.

One Head — close to the tunnel mouth — swiveled its huge, swollen helmet-skull towards her.

She ducked back into the tunnel, aware that all her cilia were quivering.

Strong-Flukes drifted to the tunnel floor, landing in a little cloud of food particles. “Heads,” she said, her voice soft with despair. “We can’t fight Heads.”