"Thank you." As they shook hands again, Alek felt a burden lift, knowing that Dylan would keep his word. After a month of being betrayed - by his family, his country's allies, and his own government - it was a relief to trust someone.

He shivered and stamped his feet. "Shall we get out of this cold?"

"Aye. A hot cup of tea would be brilliant."

"We can build a fire!" Alek said, realizing that there was no need to hide their smoke anymore. Another good thing about helping the Darwinists - he could have a warm bath and a hot meal for the first time in weeks.

Dinner was an extravagant affair, but bathing was better.

First Bauer packed the tub with snow, then melted it with pots of boiling water. The resulting bath was deliciously hot, and for the first time in a month removed the engine grease from under Alek's fingernails. With a lady present, Klopp, Bauer, and Hoffman all shaved, and Dylan complained loudly that he hadn't brought his razor, though the boy hardly seemed to need it.

Dr. Barlow, of course, was disinclined to bathe in a castle full of men. But when Dylan didn't take advantage of the bathtub either, Alek wondered if hot water flowed freely aboard the Darwinists' airship.

Hoffman thawed a lamb over the fire, while Master Klopp and Bauer cooked a vast pot of potatoes in chicken broth, onions, and black pepper. The feast went on past dark, despite how exhausted they all were.

It was refreshing to have a lady at the table. As Alek had suspected, Dr. Barlow's spoken German was quite fluent. And Dylan somehow managed to make the other men laugh with only the words he'd picked up in one day.

As the night drew on, Alek began to wonder when next he would see an unfamiliar face. After hiding for five weeks, he'd already half forgotten what it was like to meet a new person, or to make a new friend.

What if he were stuck in this castle for years?

The next morning Alek's first steps were slow ones.

The sledge wouldn't budge at first, like a dog refusing to take a walk. But finally its runners cracked their overnight coat of ice and began to scrape along the courtyard stones.

As the Stormwalker neared the gate, Alek wondered if the sledge behind them was straight.

Master Klopp read his mind. "Perhaps I should watch out the hatch, like Volger."

"No offense, Klopp," Alek said, "but you're a bit too sturdy to stand on my shoulders."

The master of mechaniks shrugged, looking relieved.

"Perhaps Mr. Sharp can help," Dr. Barlow suggested in German. She was sitting in the commander's chair again, Tazza at her feet.

Alek agreed, and soon Dylan was halfway up through the hatch, facing backward, his boots settled on Alek's shoulders.

"At least we know the sledge fits through the door," Klopp muttered. "Since it is the door."

After a few bumps and scrapes they were out on the open ice. But dragging the sledge was still like walking through molasses. Every step set the engines groaning. Annoyingly, Dylan stayed up top, his boots bouncing on Alek's shoulders.

"Be ready to speed up a bit," Klopp said as they reached the slope leading down from the castle. "We don't want our cargo sliding into us from behind."

Alek nodded, grasping the saunters tighter. Going down the hill, the sledge would build up its own momentum.

With a metal clang Dylan dropped back down into the cabin.

"They're here!"

They all looked at him, speechless.

"To rescue us!" he shouted. "Two airships, coming over the mountains ahead!"

Alek brought the Stormwalker to a quick halt, looking at Klopp. "Cut us loose. We need to get Volger back!"

"But they'll think we're attacking."

"Wait a moment, both of you," Dr. Barlow said. "According to the captain the Air Service shouldn't be here for a week!"

Master Klopp didn't answer, leaning forward and raising his glasses to his eyes. His gaze swept the sky a moment, then fixed on a single spot, a frown growing on his face.

Alek squinted out the viewport and saw them - two dots just above the horizon. He silenced the walker, listening for the sound of the airship's engines across the snow.

"Not airbeasts," Klopp said simply. "They're the kaiser's zeppelins, coming for the kill."

THIRTY-ONE

Deryn listened to the old mechanic arguing with Alek.

She didn't have to speak Clanker to know what they were saying  - she'd heard the word "zeppelin" come from Klopp's mouth. So it wasn't rescuers coming ...

It was barking Germans!

She reckoned Klopp wanted to slink back to the castle and let the zeppelins do their work. The airships wouldn't have spotted the Stormwalker yet. So once the Leviathan was destroyed, Alek and his friends could go back into hiding.

Dr. Barlow was about to join the argument, but Deryn silenced her with a hand on one shoulder, knowing exactly what to say.

"Your friend Volger's out there, Alek. Because he traded himself for you!"

"I know that," Alek said. "But it seems Volger planned for this. He made Klopp promise to keep me hidden if the Germans came."

Deryn sighed. That count was a shifty one.

Alek switched back to Clanker-talk, ordering Klopp to disconnect the walker from the sledge. It was odd how many words in German were almost the same as in English, once you'd got your ear in. For once, though, Alek wasn't getting his way. The old man folded his arms, and kept saying nein and nicht, which any dafty could tell were Clanker for "no."

And it was obvious Bauer and Hoffman would obey Klopp, not Alek, however important the boy was back in Clanker-land. Without their help the Stormwalker was stuck here, like a dog tied to a stake.

Deryn drew her rigging knife, but reckoned that holding it to Alek's throat wouldn't work twice. Besides, she'd promised not to.

But it was time for this squabble to end.

With the hilt of the knife she thumped Klopp hard on his pointy helmet. It slipped down over his eyes, squelching his latest argument.

She turned to Alek. "Give me an axe."

Deryn was down the chain ladder in a squick, the axe thrust through her safety harness. The snow was deep here on the slope, filling her boots with murderous cold as she trudged up to the sledge.

She'd watched Klopp rig this contraption, so she knew its weakness. The ends of the chain were welded to two iron posts on the front of the sledge, the chain's length threaded through a steel ring at the Stormwalker's waist. If she cut either end, the chain would slide through the ring and out, freeing the walker.

But it was massive, each link as big as Deryn's hand. She chose the right side of the sledge. The welding looked hasty there, the wood of the sledge dotted with globs of metal. She scooped up snow in her gloved hands and packed it around a link of chain. Hopefully Alek was right and the freezing cold would make the metal brittle.

"All right, then," she said, raising the axe. "Break!"

Her first swing bounced limply back. The chain was too slack to take the force of the blow.

"We don't have time for this!" she cried, glancing at the horizon. The two airships were close enough for her to see their markings now - Iron Crosses on their tail fins, their skins silvery in the morning sun.

"Mr. Sharp!" called Dr. Barlow, her head sticking up from the Stormwalker's hatch. "Anything we can do?"

"Aye," Deryn shouted. "Pull it tight!"

Dr. Barlow disappeared, and a moment later the Stormwalker's engines surged. It took a shuffling step ahead, the chain snapping taut. The sledge shifted a bit beside Deryn as she packed more snow.

Her next swing hit the unyielding metal hard, sending a nasty shock up her arms. She knelt to look closer: The blow had left a notch in one of the metal links, and another in the axe. But the chain wasn't split.

"Blisters."

"Anything?" Dr. Barlow called.

Deryn didn't answer, swinging again as hard as she could. The axe bounced from her hands - she leapt back as it spun through the air, landing a few yards away.

"Careful, Mr. Sharp!" the lady boffin admonished.

Deryn ignored her, peering closer. One link of the chain showed a tiny fracture, too narrow for another link to slip through.

But under enough force the metal might bend.

She called up to the Stormwalker, "Tell Alek to pull -  as hard as he can!"

Dr. Barlow nodded, and soon the Stormwalker began to roar again. The machine shifted from foot to foot, digging itself deeper into the snow. Sparks glimmered as its metal feet scraped bare stone below. The sledge crept forward a bit, nudging at Deryn's knee like some huge dim beastie trying to get her attention.

The broken link was bending, the fissure stretching wider with every surge of the walker's engines. Deryn took a wary step back. The chain was going to lash out like a giant metal bullwhip when it finally pulled free.

She scanned the horizon. The two airships had split apart to come at their prey from opposite directions. The sky rippled as the Leviathan's flocks took to the air. But the whale itself lay motionless on the ground, helpless to escape the Clankers' approach.

"Blister this!" Deryn trudged to where the axe had fallen and pulled it from the snow. One good wallop anywhere along the chain would pull that barking link open.

She grabbed a loose cargo strap to brace herself, listening to the surges of the Stormwalker for a moment. When she had its rhythm in her head, Deryn raised the axe in one hand, and brought it down just as the engines hit the peak of their roar... .

The chain split, whipping away too fast to see. As the suddenly freed walker staggered ahead, the links threaded through the metal ring at its waist, rattling like a Maxim gun. The loose end flailed for a few seconds, snapping wildly about the walker's head and driving the startled lady boffin back inside.

But the chain was still attached to the left side of the sledge ... and as the loose end slipped through the steel ring on the Stormwalker, the whole length flung itself back at Deryn.

She dove into the snow, and heard the metal whipping past overhead. It smacked against the cargo on the sledge, slashing through sacks of flour - a spray of white dust filled the air.

"BREAKING THE LINE."

The chain dropped to the snow and slithered away, meekly following the staggering walker, its energy finally expended.

Deryn stood up, coughing out the dry taste of inhaled flour.

Something was nudging at her knee... .

The sledge was pushing her insistently, its speed building. But what was pulling it? Then she realized what had happened. The last jerk of the chain had got it started down the slope.

"Oh, that's brilliant!" Deryn said, scrambling aboard the sledge. The shush of runners on the snow grew louder as she spat more flour from her mouth.

Before her the Stormwalker had come to a halt, facing away. Alek was waiting for her to climb back up the ladder.

The sledge was headed straight for the walker's legs!

Standing up unsteadily on a bag of dried apricots, Deryn cupped her hands and yelled, "Dr. Barlow!"

No answer came, and no one poked their head from the hatchway. What were they doing in there? Playing Parcheesi?

The sledge was still building speed.

"Dr. Barlow!" she screamed again.

Finally a black bowler emerged from the hatch. Deryn waved her arms, trying to indicate the sledge, movement, and the general notion of destruction. The boffin's eyes widened as she saw their recently freed cargo bearing down on them.

She disappeared again.

"About time," Deryn said, crossing her arms.

It was lucky she'd scrambled aboard. The sledge was building momentum every second, already sliding faster than Deryn could have run in this snow. She grabbed the loose strap again, not wanting to fall and wind up a greasy spot in the sledge's tracks.

The Stormwalker was finally moving again, taking a ponderous step forward. The machine wavered a bit, like a dim-witted beastie wondering whether to run from some predator.

Deryn frowned, hoping that they wouldn't scamper off for the battle without her. But Alek didn't seem like the type to leave one of his crew behind.

Dr. Barlow popped up again, and the walker's engines roared to life. She was shouting down into the cabin, guiding Alek in some boffin-inspired strategy.

But the sledge was still catching up, building speed faster than the Stormwalker on the ice-crusted snow. Deryn looked up at the cargo towering over her. If the two giant objects collided, she was going to be right in the middle of it.

"Get going!" she cried, climbing higher on the pile.

The Stormwalker drew closer and closer, and Deryn realized that Dr. Barlow had gone barking mad. She wasn't even trying to get out of the way. The walker was keeping a steady pace, just a squick slower than the sledge.

She pantomimed confusion for Dr. Barlow, and the lady boffin made climbing gestures in reply.

Deryn frowned, then saw the ladder hanging from the Stormwalker's belly hatch. It flailed in the air as the machine ran, trailing behind like some daft child's broken kite string.

"Oh, you're not thinking I should grab on to that," she muttered. The ladder was all chains and metal rungs -  heavy enough to knock a tooth out!

Deryn crossed her arms. She could climb up into the walker once the sledge came to a halt, couldn't she? Of course, the quicker she got aboard, the sooner they could go help the Leviathan.

Across the ice, the Clanker airships were making their first pass. Machine guns flickered from their gondolas, a cloud of fl¨¦chette bats swirling around them. She could see how small the zeppelins were now - barely two hundred yards long. But the Leviathan was almost helpless beneath them, her flocks hungry and battered from last night's battle.

"No barking choice, I suppose," she muttered.

The Stormwalker drew nearer, so close that its giant feet were kicking snow back into her face. But the ladder flailed just out of reach. Deryn edged to the front end of the sledge, balanced precariously on a barrel of sugar. Still, she couldn't reach it. She was going to have to jump.

Deryn readied herself, flexing her hands and trying to see some pattern in the ladder's thrashing.

Finally she leapt into the air ...

Her fingers closed around a metal rung, and she found herself swinging forward between the walker's legs. The engine noise was deafening. Gears and pistons clanked and gnashed about her, and a pair of exhaust pipes hissed hot black smoke into her face. Her grip was jolted with every giant step, her feet swinging wildly. The ladder twisted in the air, whirling Deryn like a drop spindle.

She thrashed her feet until one boot caught a lower rung, anchoring the ladder - the world stopped gyrating.

Glancing up, she saw Bauer and Hoffman peering down from the darkness of the belly hatch. Bauer's hand was out. All she had to do was climb a few meters.

As if that were easy.

Deryn reached up to grab the next rung. The metal was jaggy, gripping her gloves with little teeth. She pulled herself grimly upward, trying to ignore the spikes arrayed around the hatch.

"CLAMBERING UP INTO THE GEARS."

Finally she was close enough to reach up and take Bauer's hand. Hoffman grabbed hold, and the two of them pulled her inside in a squick.

"Willkommen an Bord," Bauer said with a smile, meaning "Welcome aboard," of course.

Blisters, but Clanker-talk was easy.

THIRTY-TWO

"You're white as a ghost!" Dr. Barlow said.

"It's only flour." Deryn pulled herself the rest of the way into the pilot's cabin with a groan. Her hands ached from clinging to the flailing ladder, and the muscles in her arms were howling. Her heart still beat like a hammer.

"Flour?" Dr. Barlow said. "How odd."

"Well done, Dylan!" Alek was twisting at the controls. "I've never seen anyone come aboard a walker that way!"

"I wouldn't recommend it." She plonked down on the lurching cabin floor, panting hard. Tazza crept over to nuzzle her hand, then sneezed out a snootful of flour.

Within moments Deryn felt dizzy from the walker's motion. The trip out to the castle had been bad enough -  the screech of metal against metal, the smell of oil and exhaust, and the endless, murderous noise of the engines. But at full trot, riding in the walker was like being shaken in a tin snuffbox. No wonder the Clankers wore those silly helmets; it was all Deryn could do to keep her head from banging against a wall.

Klopp, who was peering out the viewport through field glasses, said something in German to Alek.

"I thought he wasn't helping," Deryn muttered.

"That was when we could hide," Dr. Barlow said. "Now that the Germans have certainly seen us, he's changed his tune. If we don't shoot both of those zeppelins down, they'll report about our Austrian friends."

"Well, he might have made up his mind a bit faster." Deryn looked down at her aching hands. "I could've used some help cutting that chain."

Dr. Barlow patted her shoulder. "You did well, Mr. Sharp."

Deryn shrugged off the compliment and stood up. She'd had enough of being bounced about blindly. Grabbing on to two hand straps that hung from the ceiling, she pulled herself up and out the top hatch.

The cold hit her full in the face. It was like being on the spine of the airship in a storm, the horizon lurching around her with every step.

Deryn squinted into the eyeball-freezing wind. The zeppelins were skimming low, dragging ropes along the ground. Men slid down them, landing in the snow with guns and equipment on their backs.

But why bother? If they wanted to destroy the Leviathan, they could stay up high and use phosphorous bombs.

She dropped back inside. "They're putting men down."

"Those are Kondor Z-50s," Alek said. "They carry commandoes instead of heavy weapons."

"It seems their objective is to capture our ship," Dr. Barlow said.

"Blisters!" Deryn swore. A live hydrogen breather in the Clankers' hands would be a disaster; they'd learn everything there was to know about the great ship's weaknesses. "But aren't they afraid of us?"

"They'll have anti-walker guns aboard," Alek said grimly. "They can't fire them from the air. But from the ground, they'll give us a fight."

Deryn swallowed. It was bad enough, riding in this contraption. But the thought of being broiled alive by some armor-piercing shell made her ill.

"We need your help again, Dylan."

She stared at Alek. "Do you want me to drive this barking contraption now?"

"No," he said. "But tell me, do you know how to fire a Spandau machine gun?"

Deryn knew no such thing, but she'd fired an air gun plenty of times.

This was quite different, of course. Like everything else made by Clankers, it was ten times louder, shakier, and more cantankerous than it looked. When she gave the trigger a test squeeze, it rattled like a piston in her hands. Bullet casings spewed from its side, bouncing from the cabin wall in a hot metal hail.

"Cripes!" she swore. "How do you hit anything with this?"

"Simply point it in the general direction," Dr. Barlow said. "What the Clankers lack in finesse they make up for with blanket ruination."

Deryn leaned forward, squinting out the tiny peephole. All she could see was snow and sky bouncing along. She felt claustrophobic and half blind. It was the opposite of watching from the Leviathan's spine, with the battle spread out below like the pieces on a chessboard.

She glanced over at Klopp, who was manning the other machine gun. Instead of looking out, he was waiting for Alek to tell him when to fire.

"Stuff this. I'll be back in a squick," Deryn said, pulling herself up through the hatch again.

Both Kondors had dropped commandoes now. One group was storming toward the Leviathan, their zeppelin supporting them with machine-gun fire. The other bunch was assembling some sort of artillery, a long-barreled field gun that was pointed straight at the Stormwalker.

"Oh, blisters," she said.

"DIE ANTI-WANDERPANZER TRUPPEN."

The Clankers worked swiftly, and a moment later the gun's muzzle erupted with flame. The walker twisted beneath her, throwing her hard against the side of the hatch. She barely kept from falling back through, her feet flailing below.

For a moment Deryn thought they'd been hit. But then she felt the shell whiz by, her ears popping as its passed. The Stormwalker staggered into a long turn, finally regaining its balance on the snow.

Alek was either barking brilliant at the controls, or he was completely mad. They were headed straight for the anti-walker gun, lurching back and forth across its sights while the crew desperately reloaded.

Deryn dropped back inside and took her machine gun, aiming it low. She reckoned they'd be among the Germans in another five seconds, if they hadn't already been blown to blazes.

"Get ready!" Alek shouted.

Deryn didn't wait, and squeezed the trigger. The gun jumped and rattled in her hands, spewing death in all directions. A few dark shapes slipped past her peephole, but she had no idea whether they were men or rocks or the anti-walker gun.

A metal clank shook the cabin, and suddenly the world was staggering to port. Deryn was thrown from her gun, her feet slipping on spent casings rolling across the floor. She landed on something soft, which turned out to be Dr. Barlow and Tazza huddled in the corner.

"Sorry, ma'am!" she cried.

"Not to worry," the lady boffin said. "You really are quite insubstantial."

"I think we hit it!" Alek said, still twisting at the controls.

Deryn scrambled to her feet and pulled herself up and out the hatch again. Behind them the anti-walker gun lay wrecked in their giant footprints - overturned, the barrel bent. Its crew were scattered, a few motionless, the white snow about them flecked with vivid red.

"You stomped it, Alek!" she shouted down, her voice hoarse.

She spun around to face forward. The Stormwalker was headed for the other group of commandoes now. They were hunkered down in the snow, an aerie of strafing hawks skimming over them, razor talons glimmering in the sun.