Wind pushed at her from behind; Venera had to consciously set her feet down, grinding them into the grit to prevent herself starting to run. Giving into that run would be fatal, Diamandis assured her. The reason why emerged slowly, horribly, from around the collapsed walls and tangled groves of once-great estates.

She clapped Diamandis on the shoulder and pointed. “How long ago?”

He nodded and leaned in so that she could hear him over the roar. “A question important to our enterprise. It happened generations ago, in a time of great unrest in the principalities. Back when the great nations of Spyre still traveled—before they began to hide in their fortresses.”

A hundred yards or so of slick decking extended past the last broken stones, then the first tears and gaps appeared. Long sheets of humming metal extended out, following the lines of the girders that underlay Spyre’s upper skin. Soon even they disappeared, leaving only bright shreds and the girders themselves. A latticework of metal beams was all the ground there was for the next mile.

Below the plain of girders dark clouds shot past with dizzying speed. Propelled by Spyre’s centrifugal force, a ceaseless hurricane roared in and down and through the empty windows of the broken ruins and leaped off the edges of the world.

“Behold the airfall!” Diamandis gestured dramatically; but there was no need. Venera stood awestruck at the sheer savagery of the permanent storm that warred about her. If she lifted one foot or straightened her back she might be caught and yanked out and then down, and shot out of Spyre through this screaming, gouting wound.

“This—this is insane!” She hunkered down, clutching a boulder. Her leathers flapped up around her ears. “Am I expected to run into that?”

“No, not run! Crawl. Because up there—do you see it? There is your fourth alternative!” She squinted where he pointed and at first didn’t see anything. Then she blinked and looked again.

The skin of Spyre had been stripped away for at least a mile in every direction. The hole must have unbalanced the whole wheel—towers, farms, factories, and even perhaps whole towns being sucked out and flung into the depths of Virga in a catastrophe that threatened to destroy the entire wheel. For some reason the peeling and collapse had propagated only so far and then stopped—but the standing cyclone of exiting air must have shaken Spyre so much as to threaten its immediate destruction.

This, if anything, explained the preservationists and the fierce war they had fought to lay their tracks around Spyre. The unstable wobble of the wheel could only be fixed by moving massive weights around the rim to balance it. There was no patching this hole.

Everything above had been sucked out as the skin peeled away—except in one place. One solitary tower still stood a quarter mile into the plain of girders. It had the great fortune to have been built overtop a main intersection point for Spyre’s skeletal system. Also, the place might once have been a factory with its own reinforced foundation, for Venera could see huge pipes and tanks splayed like the roots of a tree below the girders. The tower itself was dark as the clouds that framed it, and it slowly swayed under the force of the winds. The girders bounced it like an acrobat in a net.

Just looking at it made her nauseated. “What is that?”

“Buridan Tower,” said Diamandis. “It’s our destination.”

“Why? And how are we going to get there through… through that?”

“Using our courage, Lady Fanning—and my knowledge. I know a way, if you’ll trust me. As to why—that is a secret that you will reveal, to both of us.”

She shook her head, but Venera had no intention of backing out now. To do anything else but go forward in this mad adventure would be to invite relaxation—and thought. Grief drove her on, an active refusal to think. She waited, eyes tearing from the wind, and eventually Diamandis nodded sharply and gestured come on.

They crept across the last acre of intact skin, grabbing onto every rock and jammed tree branch that might offer purchase. As they approached a great split in the metal sheeting, Venera saw where Diamandis was going, and she began to think that this passage might be possible after all.

Here, a huge pipe ran under Spyre’s topsoil and skin. It was anchored to the girders by rusting metal straps and had broken in places, but extended out below the skinless plain. It seemed to head straight for swaying Buridan Tower.

Diamandis had found a hole in the pipe that was sheltered by a tortured dune. He let himself down into the black mouth and she followed; instantly the wind subsided to a tolerable scream.

“I’m not even going to ask how you found this,” she said after dusting herself off. He grinned.

The pipe was about eight feet across. Sighting down it she beheld, in perspective, a frozen vortex of discolored metal and sedimented rime. Behind her it was ominously dark; ahead, hundreds of gaps and holes let in the welling light of Candesce. In this new illumination, Venera eyed their route critically. “There’s whole sections missing,” she pointed out. “How do we cross those?”

“Trust me.” He set off at a confident pace.

What was there to do but follow?

The pipe writhed in sympathy with the twisting of the beams. The motion was uncomfortable, but not terrifying to one who had ridden warships through battle, walked in gravities great and small throughout Virga, and even penetrated the mysteries of Candesce—or so Venera told herself, up until the tenth time her hand darted out of its own accord to grip white knuckled some peel of rust or broken valve-rim. Rhythmic blasts of pain shot up her clenched jaw. An old anger, born of helplessness, began to take hold of her.

The first gaps in the pipe were small, and thankfully overhead. The ceiling opened out in these places, allowing Venera to see where she was—which made her duck her head down and continue on with a shudder.

But then they came to a place where most of the pipe was simply gone, for a distance of nearly sixty feet. Runnels of it ran like reminders above and to the sides, but there was no bottom anymore. “Now what?”

Diamandis reached up and tugged a cable she hadn’t noticed before. It was bright and strong, anchored here and somewhere inside the black cave where the pipe picked up again. Near its anchor point the line was gathered up and pinched by a huge spring, allowing it to stretch and slacken with the twisting of the girders.

“You did this?” He nodded; she was impressed and said so. Diamandis sighed. “Since I’ve had no audience to brag to, I’ve done many feats of daring,” he said. “I did none in all the years when I was trying to impress the ladies—and none of them will ever know I was this brave.”

“So how do we… Oh.” Despite her pounding headache, she had to laugh. This was a zip line; Diamandis proposed to clip rollers to it and glide across. Well, at least the great girder provided a wall to one side and partial shelter above. The wind was not quite so punishing here.

“You have to be fast!” Diamandis was fitting a pulley-hold onto the cable. “You can’t breathe in that wind. If you get stranded in the middle you’ll pass out.”

“Wonderful.” But he’d strapped her into the harness securely, and falling was not something that frightened people who lived in a weightless ocean of air. When the time came she simply closed her eyes and kicked off into the white flood.

They had to repeat this process six times. Now that he had someone to give up his secret to, Diamandis was eager to tell her how he had used a powerful foot-bow to shoot a line across each gap, trusting to its grip in the deep rust on the far side to allow him to scale across once. After stronger lines were affixed it was easy to get back and forth.

So, walking and gliding, they approached the black tower.