She squinted, watching for confirmation from below. The light flashed in answer: W-H-A-T - M-A-N-N-E-R-?

W-A-L-K-E-R - T-W-O - L-E-G-S, she answered.

Another confirmation flashed, but that was all. They'd be scrambling now, trying to mount some defense against an armored attack. But what could the Leviathan's crew do against an armored walker? An airship was defenseless on the ground.

They needed more details. She raised the glasses to her face again, trying to read the markings on the machine.

"Alek, you bum-rag!" she cried. Two steel plates hung down to protect the walker's legs, both painted with the Iron Cross. And a double-headed eagle was painted on its breastplate. Alek was no more Swiss than he was made of blue cheese!

"Beastie, wake up," Deryn snapped. She took a breath to steady herself, then said in a slow, clear voice, "Alert, alert. Regards to the Leviathan from Midshipman Sharp. The approaching walker is Austrian. Two legs, one cannon, type uncertain. It must be Alek's - that boy we caught - family on their way. Maybe he can talk to them... ."

Deryn paused for a moment, wondering what else to say. She could think of only one way to stop the machine, and it was too complicated to cram into a lizard's drafty wee attic.

"End message," she said, and gave the beastie a shove. It scuttled away down the ascender's rope.

As she watched its progress, Deryn let out a soft groan. Away from her body heat the freezing air was slowing it down. The beastie would take long minutes to deliver the message.

She peered across the glacier again, using only her naked eyes. A tiny flash of metal winked at her from the snow, closer to the airship every second. The charging walker was going to arrive before the lizard.

Alek was the key to stopping the machine, but in all the ruckus would anyone think of him?

The only way to make sure was to go down herself.

TWENTY-EIGHT

This was Deryn's first sliding escape.

She'd studied the diagrams in the Manual of Aeronautics, of course, and every middy in the Service wanted an excuse to try one. But you weren't allowed to practice sliding escapes.

Too barking dangerous, weren't they?

Her first problem was the angle of the cable stretching down to the airship. Right now it was much too steep; she'd wind up a splotch in the snow. The Manual said that forty-five degrees was best. To get there the Huxley needed to lose altitude - fast.

"Oi, beastie!" she yelled up. "I think I'll light a match down here!"

One tentacle coiled serenely in the breeze, but otherwise the airbeast didn't react. Deryn growled with frustration. Had she found the one Huxley in the Service that couldn't be spooked?

"Bum-rag!" she called, bouncing in the saddle. "I've gone insane, and I'm keen to set myself on fire!"

More tentacles coiled, and Deryn saw the venting gills softly ruffle. The Huxley was spilling hydrogen, but not fast enough.

She kicked her legs to swing herself back and forth, yanking on the straps that connected her harness to the airbeast. "Get down, you daft creature!"

Finally the smell of hydrogen filled her nose, and Deryn felt the Huxley descending. The tether line looked less steep every second, like the string of a falling kite.

Now came the tricky part - reconfiguring the pilot's harness into an escape rig.

Still yelling at the beast, Deryn began to take apart the harness. She loosened the straps around her shoulders, wriggling one arm free, then the other. As the belt around her waist unbuckled, the first wave of dizziness hit. Nothing was keeping her in the saddle now except her own sense of balance.

Deryn realized she'd been awake almost twenty-four hours - if you didn't count lying unconscious in the snow, which was hardly quality sleep. Probably not the best time for risky maneuvers ...

She stared at the undone straps and buckles, trying to remember how they went back together. How was she meant to reassemble them while clinging to her perch?

Sighing, Deryn decided to use both hands - even if that meant she was one Huxley twitch away from a long fall.

"Forget what I was saying earlier, beastie," she murmured. "Let's just float calmly, shall we?"

The tentacles stayed coiled around her, but at least the creature was still descending. The tether line had almost reached forty-five degrees.

After a long minute's fiddling, the escape rig looked right - the buckles forming a sort of carabiner in the center. Deryn gave the contraption a jerk between her hands, and it held firm.

Now came the scary part.

She clenched the rig between her teeth and pulled herself up with both hands. As her bum left the saddle, a fresh wave of dizziness hit. But a moment later Deryn was standing in a half crouch, her rubber-soled boots gripping the curved leather seat.

She reached up and clipped the buckles onto the tether line, then took one end of the strap in each hand, winding the leather several times around her wrists.

Deryn glanced down at the glacier. "Blisters!"

While she'd been getting ready, the walker had closed almost half the distance to the airship. Worse, the tether line had gotten steeper. The wind was tugging the Huxley higher. At this angle she'd slide down the rope much too fast. The Manual was full of gruesome tales about pilots who'd made that mistake.

Deryn stood to her full height, her head inches from the Huxley's membrane.

"Boo!" she cried.

The airbeast shivered all over, venting a bitter-smelling wash of hydrogen right into her face. The saddle jerked beneath Deryn, and her boots slipped from the worn leather ...

A fraction of a second later the straps around her wrists snapped, yanking her shoulders hard. And she found herself sliding down toward the massive bulk of the airship below.

She felt nothing but a roar in her ears, like staring into a headwind on the spine. Tears streamed from her face, freezing to her cheeks, but Deryn found herself letting out a wild, exultant scream.

This was real flying, better than airships or ascenders or hot-air balloons, like an eagle zooming down toward its prey.

For a few terrifying seconds the angle grew steeper, but the Manual had predicted that. It was the Huxley springing up behind Deryn as her weight slid away from it.

She glanced up at the rig. The metal buckles were giving off an audible hiss and a squick of smoke from the friction. But she was moving too quickly to burn through the rope. Everything was going perfectly.

"EMERGENCY ZIP LINE."

As long as another gust of wind didn't pull the Huxley higher ...

The airship grew in front of her. The crew were already scrambling, a muddle of tiny dots swarming on the snow. That was good. She didn't have time to make a formal report. She had to get to the machine room and back out before the walker arrived ...

But what was that? From out of nowhere a small shape had appeared on the rope ahead - a tangle, or some imperfection in the cable. At this speed, running into a knot could break her wrists - or even worse, snap the leather of the rig.

Then Deryn realized what it was: the message lizard, still making its plodding way down toward the ship.

"Out of the way, lizarrrrrrd!" she screamed.

At the last moment the beastie heard her - and leapt straight into the air! Deryn whipped past it, spinning herself around to look back. The lizard came down onto the rope, wrapping its sticky feet around the cable and shrieking random warnings as Deryn zipped away.

"Sorry, beastie!" she cried, then spun back toward the airship.

It was coming at her so fast.

She tried to slow herself, letting her legs dangle to catch the air. At least the membrane was squishy and half deflated. The flank was seconds away now, sniffers and riggers scrambling to get out of her way. Deryn let the straps around her wrists unwind ...

At the last second she dropped.

The membrane crumpled around her with a whump. For a moment she was buried in the warm, smothering embrace of the airbeast's skin, breathless and dazed.

She rolled over to face upward, her ears still ringing with the impact, and found herself nose-to-nose with a curious hydrogen sniffer.

"Ow," Deryn told it. "That hurt."

The beastie sniffed her and let out a concerned bark -  apparently the impact had popped open a leak.

Hands reached down and pulled her up, setting Deryn onto her feet.

"You all right there, lad?"

"Aye, thanks," she said, looking around for an officer. But none had appeared to demand a report. The riggers were in motion all around her, the crew scattering below. "Is it in sight yet?"

"You mean that contraption?" The rigger turned and looked across the snow. On the horizon a squick of a reflection pulsed in a steady pattern, matching the rhythm of the walker's stride. "They say it's a big one."

"Aye, it is," Deryn said, and headed down.

Dashing across the membrane on shaky legs, she hoped that Alek was still with the eggs. Would he guess what the ringing battle Klaxon meant and try to escape? Or, with the enemy approaching, would some daft officer decide to lock him up again?

The faster she found him, the better.

Spotting a tangle of ratlines draped across the main gondola, Deryn didn't bother using a gangway. She climbed down the ropes, swinging into the gondola through a smashed window. Shards of broken glass tugged at her flight suit, but the suit's thick leather snapped them from the frame, her boots skidding as she landed.

There was no chaos inside, just controlled urgency. A troop of men ran past, carrying small arms. A chorus of command whistles sounded, calling for the hawk tenders to assemble.

But air guns and aeroplane nets against an armored walker? They wouldn't stand a chance.

The machine room was just down the corridor. She headed toward it, then burst through the door at a run.

"Mr. Sharp!" Dr. Barlow said from the darkness. "What's all the fuss out there?"

A moment later Deryn's eyes adjusted - there he was, kneeling by the cargo box.

"Alek!" she cried. "It's your family!"

He stood, letting out a sigh. "As I expected."

"They've sent an emissary?" Dr. Barlow asked.

"They've sent a barking war machine!" Ignoring the boffin's expression, Deryn grabbed Alek's arm and pulled him out the door.

Once she'd dragged him into the corridor, he began to run under his own power. She led him toward the lower deck.

"I thought Volger might take a direct approach," he said as they scrambled down the stairs.

"Speaking of direct, how come you didn't mention that your family had a barking walker?"

"Would you have believed me?"

"I'm still not sure I believe it!"

On the lower deck, Deryn ran for the gondola's main door. But when they reached the gangway, it was already occupied by a line of crewmen carrying heavy crates. The words "high explosives" brought Deryn to a skidding halt.

"Don't want to bump into these fellows. Aerial bombs."

Alek's eyes widened. "What are they going to drop them from?"

"A Huxley, maybe? Just what we need to start that walker of yours shooting!" She pulled him away. "Come on, we'll jump out a window."

At the middies' mess the broken window they'd passed that morning still hadn't been repaired. Deryn jumped up onto the ledge, but paused. With the gondola at this angle the drop was a bit farther than she'd expected.

Alek climbed up beside her, looking down dubiously.

"The snow's dead soft," Deryn said, trying to convince herself. "It's an easy jump!"

"After you, then," Alek said.

"No chance." Deryn grabbed his arm, and off they went.

It wasn't so bad. The snow compacted beneath them with a muffled crunch, like being whacked with a big freezing pillow.

Alek rose to his feet, glaring. "You pushed me!"

"More of a pull, really." She pointed across the snow. "No time to dawdle."

The walker was almost here.

As they ran, Deryn could feel the machine's footsteps rumbling beneath her now, and the roar of its engines shaking the air. Its huge feet thrashed the snow, raising white clouds in its wake.

"At least they aren't shooting yet."

"They're well within range," Alek said. "But they don't want me getting hurt."

"That's what I'm counting on." She pulled him across the snow, past the crewmen arrayed to defend the ship.

Deryn could see now what the captain was planning. A second ascender was in the air - Newkirk aboard, clutching an aerial bomb in his arms. More bombs lay half buried in the snow ahead, wires running to them. If the walker stumbled too close to one, maybe they could blast it off its feet.

As she and Alek ran through the defenses, someone called after them. But Deryn pretended not to hear. She had to get Alek out in front before the shooting started.

"Do you reckon they can see us yet?" she asked.

"Let's make sure." Alek slowed, waving his arms.

The walker thundered toward them for another few seconds, then suddenly tipped backward. Deryn thought for a moment that it was going to fall. But then one steel leg stretched out in front, plowing through the snow and bringing the machine to a sliding halt, an icy cloud drifting up around it.

"Nicely done, Klopp," Alek murmured, and turned to Deryn. "They see us."

"Brilliant! Oh, and sorry about this." Deryn grabbed Alek's arm, drew her rigging knife, and pressed it against his throat.

"What are you - ," he started, but the words choked off as cold metal touched his flesh.

"Don't struggle, you ninny!" she hissed. "Do you want your head cut off? I'm just making sure no one gets hurt."

"I fail to see your logic!" Alek growled at her, but he stopped struggling.

As she stared up at the huge machine, Deryn put a defiant scowl on her face. The walker stood there, utterly motionless, as if transformed into a vast iron statue.

"NEGOTIATIONS AND COLLATERAL."

"Hey, in there!" she yelled. "Don't move or I'll spill your friend's guts!"

"If you do that," Alek pointed out, "they'll simply blow you to pieces."

"Don't be daft," she whispered. "I'm not really going to ..."

Her voice trailed off as the machine's head began to move. Two sets of steel teeth slowly opened, revealing a pair of faces inside.

"Hah!" Deryn said. "They can see us for sure now."

Alek sighed. "Yes, but what do you expect them to do? Surrender to the superior force of your knife?"

"Well ..." Deryn frowned. "I hadn't really thought past this bit."

Alek looked at her. "You really are a ninny, aren't you?"

"Me, a ninny?" Deryn cried. "I've just saved us all from getting blown up!"

"You don't really think they would have ...," Alek started, then let out a disgusted sigh. "Just yell for Volger to come down, under flag of truce. He'll know what to do."

Deryn thought this sounded sensible, whoever Volger was. She took a deep breath and shouted, "Attention, Clankers! Send down Volger, under truce."

There was a long wait. Deryn glanced up, and saw Newkirk and his ascender drifting uselessly over the airship. The wind had died. She just hoped he had a good grip on his aerial bomb.

Behind them the airship's crew was silent, the wind almost still. The only sounds were ticks and pops from the war machine as its engines cooled. She wondered if the officers would be upset about this idea of hers. No one had ordered her to use Alek as a hostage.

Of course, no one had ordered her not to either.

A soft metal groan pulled her eyes back to the walker, her grip on Alek tightening. Some sort of hatch was swinging open between the walker's legs. A ladder made of chains spilled down from it, jangling wildly for a moment, the sun flashing from its steel rungs.

A man climbed down then, slowly and carefully. Deryn noticed a sword swinging under his fur coat.

"Is that Volger?" she whispered.

Alek nodded. "I just hope your captain honors the truce."

"Aye, me too," Deryn said. One shot from that cannon could still destroy the Leviathan where it lay.

These negotiations had to work.

TWENTY-NINE

Count Volger made his way toward them, the expression on his face unreadable.

Alek swallowed. Under the circumstances, Volger was unlikely to give him the tongue-lashing he deserved. But it was humiliating enough, standing here, held hostage by a mere boy.

Volger stopped a few meters away, his eyes moving warily between the airship's crew in the distance and the blade at Alek's throat.

"Don't worry about this young fool," Alek said in German. "He's only playing at threatening me."

Volger glanced at Dylan. "I can see that. Unfortunately, those men behind you are deadly serious. I doubt we can make it back to the Stormwalker before they pick us off."

"No, but I think these people can be bargained with."

"Hey, you two!" Dylan snapped. "Stop that Clanker-talk!"

Count Volger gave the boy a bored look, then continued in German, "Are you certain he doesn't speak our language?"

"I very much doubt it," Alek said.

"Well, then," Volger said. "Let's pretend that I don't know English. We might learn something interesting if the Darwinists think I can't understand them."

Alek smiled - Volger was already taking control of the situation.

"What are you two saying?" Dylan demanded, tightening his grip.

Alek turned to face him, switching to English. "My friend doesn't speak your language, I'm afraid. He wants to meet with your captain."

The boy looked hard at Volger, then jerked his head toward the airship. "All right, let's go. But no funny business."

Alek coughed politely. "If I promise to avoid funny business, could you perhaps remove this knife from my throat?"

Dylan's eyes widened. "Oh, aye. Sorry about that."

The cold steel left his flesh, and Alek touched his neck and looked down at his hand. No blood.

"I used the dull edge, you daft git," Dylan whispered.

"Much appreciated," Alek said. "And I suppose that was quick thinking, getting me down here."

"Aye, it was," Dylan said, smiling. "Pure dead brilliant, me. I just hope the officers don't give me a good kicking for thinking for myself."