"Switch your radar to ground-scan," she said tersely. "You'll need to find someplace flat -"

"Too late," Hummingbird snapped and his breath was harsh on the comm. Gretchen cursed – the altimeter jumped and radar suddenly revealed a broad, deep canyon rushing past below her – and pulled up, turning wide around Hummingbird, whose aircraft was skidding across the crown of a mesalike hill rising above the canyon floor. The Gagarin made a swooping, leisurely circle as the other ultralight bounced to a halt and Gretchen could make out rough, jagged cliffs on every side.

"Turn all your lights on," she said, hoping Hummingbird hadn't been knocked unconscious by the violence of his landing. "And put out your anchors."

Her breath puffing white in the chill air of the cockpit, Gretchen ignored everything but the radar image of the rock and stone and precipices below as she lined up to land. "Gently now," she whispered to the Gagarin as the ultralight drifted down out of the sky, airspeed dipping low, almost into a stall. "Easy…easy…"

The front wheel touched down, sending a shock through the airframe, and then the Gagarin was rolling to a halt a dozen meters from Hummingbird.

"The number four fuel pump is clogged up," Gretchen said, her voice muffled by the cowling around the engine. White fog billowed around her shoulders, oozing from the maintenance hatch in thin streamers. "Looks like a line cracked when you crashed and has been leaking hydrogen vapor into the casing. Everything's frozen solid." A little shaky from too much adrenaline and too little rest, she climbed down from the upper wing, holding tight to the wing struts to keep from slipping.

"Can it be fixed?" Hummingbird was unloading gear from the cargo compartment. He made a vague gesture at the dark, still night hiding the rugged mesa and canyon beyond. "Here?"

Gretchen gave him a sharpish look – completely lost on the man, given the lack of light – and ran her hands over the tools on her belt. "If we have a schematic of the engine and component details, I might be able to fabricate a new fuel line or fix the old one, but I don't know if the maintenance manuals are loaded into either comp." Gretchen tried to keep her voice light, but the prospect of doubling-up in one single remaining Midge made her feel sick. We need both aircraft for the pickup, she thought desperately. The skyhook won't work with just one.

"If they're not, we're in serious trouble." Anderssen cracked frost from her gloves, keeping her eyes away from the old man. "The weight ratio in one of these aircraft is marginal with one person and supplies. Two can fit, but not with much food, water or equipment. We could probably make base camp, but I don't know how long we'd last then."

"Don't worry." Hummingbird's tone was still perfectly even. "The Cornuelle will come looking for us soon and base camp is filled with Company supplies."

"It was," Gretchen said, picking her way across splintery, loose shale. There was a bitter edge to her voice. "You're thinking everything is still in place because we left so quickly. Maybe it is, but I've never seen an abandoned camp last – and with the microbiota here – well, I think we'll find bunkers filled with calcite flowers and beautiful stone cobwebs."

"Well…" The nauallis seemed to have lost track of what he was going to say. "What can I do to help, then?"

Gretchen pulled open the door of the Gagarin and slid into her seat. The lumpy confines were starting to fit properly, but she didn't know if that was because the chair had changed or she had. Biting her lip nervously, Anderssen started to punch up a document search.

"Anchor both aircraft," she said, fighting to keep a rising tide of despair from overwhelming her. "And…and set up the tent. Find someplace out of the wind – we're all exposed up here." Her voice trailed off in surprise.

Her search for "fuel line repair" had returned an immediate hit and the comp had helpfully opened a series of v-panes on the display, showing a complete schematic of the fuel pump, the circulatory system on Hummingbird's Midge, the specifics of the lines and tubes, and a checklist showing how to repair a broken one.

"What the?" Gretchen was entirely nonplussed. "There is no way," she said to herself, tabbing through the array of documents, "Russovsky shoehorned an AI into this comp. This is impossible. Just…" She blinked, staring at the checklist. The last entry read: Buy your beautiful, smart pack-sister a drink, when we get back to the den. Paw Paw, Magdalena.

"Maggie?" Gretchen stared around the deserted, windswept mesa top in amazement. Outside, vapor was still boiling out of the damaged Midge and she could make out the outline of Hummingbird as he stomped around, stitching the anchors into the rock. A creepy shiver ran up her back, making her switch her comm to a private channel. "Can you hear me?"

There was no answer, just the usual warble of tuneless static.

"Ok…maybe dear Magdalena is psychic." Gretchen read the checklist again. Everything seemed straightforward enough, except one part about checking all of the fuel lines for microfine cracks. "How are we going to do that?"

The Gagarin rocked gently as Hummingbird unspooled an anchor line. Gretchen started to sort through her tools, reading each section of the instructions as she worked.

"All done." Hummingbird leaned against the Midge, one hand on the raised door. "I've put the tent in a crevice not too far away. Should be out of the wind." He stopped, watching her suspiciously. "What is it?"

Gretchen was regarding him appraisingly. "So, Hummingbird-tzin, an unbroken fuel line has a certain…wholeness…doesn't it? So someone with the sight should be able to see a crack or break or even a weakness – that would be a distortion of proper order, right?"

"Yes." The visible parts of Hummingbird's face became rather sour-looking. "They would."

"Good." Gretchen tapped the panel in front of her. "Here's a layout of the entire fuel system in your Midge. You need to check every centimeter for leaks or fissures. I'm going to fabricate a replacement for the broken line."

"Very well." Hummingbird stared stoically at the complicated spiderweb filling the v-pane. "Are these data on my comp?"

Gretchen nodded. "Make sure you have the hydrogen tanks locked off – we can't afford to lose any more fuel."

The old man nodded and turned away. Gretchen looked around the tiny cockpit and sighed. Too small for this job. She gathered up all her tools and plugged her hand comp into the main panel to make a copy of the instructions. "Maybe the tent is big enough."

A pale wash of violet was just beginning to tint the rim of the world when Gretchen climbed back up onto the Midge and unscrewed the engine housing. Hummingbird, wrapped in his cloak and a blanket, was squatting beside the main body of the aircraft, rubbing his hands together. Out in the open like this, without even the marginal shelter of an overhang or a cave, the night was ferociously cold.

"Pass me the other heater." Gretchen wedged the tube-shaped unit in above the pump and turned it on high-radiate. The unit was low on power, but she hoped there was just enough juice left to melt the ice and run the forced-air fan to disperse the resulting fog. While the heater hummed and glowed and blew blessedly hot air against her chest, Gretchen laid out her tools and parts on a technician's clingpad.

"You were able to make a replacement?" Hummingbird moved up next to her, angling himself into the warm draft from the heater.

"Yes," she said dryly, craning her head to peer inside the housing. "Modern science and technology triumph again. Did you check all the fuel lines?"