Dr. Barlow was tucking a black veil under her bowler, like a boffin at a funeral. "My grandfather fabricated one of these species. I wanted to taste his handiwork."

Her grandfather? Dr. Barlow had to be even younger than she looked.

"You seem surprised, Mr. Sharp. The honey is edible, is it not?"

"Aye, ma'am. Mr. Rigby makes all us middies try some." Fitzroy had made a show of screwing up his face, and Newkirk had looked ready to spew. But the taste was as good as any natural honey, really.

Deryn drew her rigging knife and reached out to the expanse of hexagonal comb, prizing a bit of honey onto its blade. She offered the knife to Dr. Barlow, who loaded a fingertip, then reached under her veil to place it between her lips.

"Hmm. Just like honey."

"Water, mostly," Deryn said. "With a few squicks of carbon for flavor."

Dr. Barlow nodded. "A very sound analysis, Mr. Sharp. But you're frowning."

"Pardon me, ma'am. But did you say your grandfather was a Darwinist? He must have been one of the first."

Dr. Barlow smiled. "He was indeed. And he had rather a fascination with bees, especially how they connected cats and clover."

"Cats, ma'am?"

"And clover, yes. He noticed that red clover flowers abundantly near towns but only thinly in the wild." Dr. Barlow rubbed her finger along the knife for another taste. "You see, in England most cats live in towns - and cats eat mice. These same mice, Mr. Sharp, attack the nests of bees for their honey. And red clover cannot grow without bees to pollinate it. Do you follow?"

Deryn raised an eyebrow. "Um, I'm not sure, ma'am."

"But it's very simple. Near towns there are more cats, fewer mice, and thus more bees - resulting in more red clover. My grandfather was good at noticing webs of such relations. You're frowning again, Mr. Sharp."

"It's just that ... he sounds like a rather eccentric gentleman."

"Some think so." Dr. Barlow chuckled. "But at times eccentrics notice things that others do not. You must sharpen your razor very well."

Deryn swallowed. "My razor, ma'am?"

The lady boffin reached out to hold Deryn by her chin. "Both sides of your face are equally smooth. But didn't I interrupt you halfway through your shave?"

As Dr. Barlow waited for an answer, the buzzing of the hives roared in Deryn's head, and the walkway seemed to tilt beneath her feet. She'd been such a ninny to muck about with razors. This was how she'd always been caught out in lies - making things too barking complicated.

"I ... I'm not sure what you mean, ma'am."

"How old are you, Mr. Sharp?"

Deryn blinked. She couldn't speak.

"With a face that smooth, not sixteen," Dr. Barlow continued. "Perhaps fourteen? Or younger?"

A squick of hope began to trickle through Deryn. Had the lady boffin guessed the wrong secret? She decided to tell the truth: "Barely fifteen, ma'am."

Dr. Barlow released her chin, giving a shrug. "Well, I'm sure you're not the first boy to come into the Service a bit young. Your secret is safe with me." She handed back the rigging knife. "You see, my grandfather's true realization was this: If you remove one element - the cats, the mice, the bees, the flowers - the entire web is disrupted. An archduke and his wife are murdered, and all of Europe goes to war. A missing piece can be very bad for the puzzle, whether in the natural world, or politics, or here in the belly of an airship. You seem like a fine crewman, Mr. Sharp. I'd hate to lose you."

Deryn nodded slowly, trying to take all of this in. "I'm in agreement with that, ma'am."

"Besides ..." A hint of a smile played on Dr. Barlow's lips. "Knowing your little secret makes it easier, should I wish to tell you some of mine."

Before Deryn had a chance to wonder what that could mean, she noticed a distant clanging over the roar of the hives.

"Do you hear that, ma'am?" she said.

"The general alarm?" Dr. Barlow nodded sadly. "I'm afraid so. It would appear that Britain and Germany are finally at war."

TWENTY

The Klaxon was ringing in triplets, the signal for an aerial attack.

"I have to run, ma'am," Deryn said quickly. "Can you make it back to your cabin alone?"

"I'd think not, Mr. Sharp. I shall be with my cargo."

"But - but ... this is an alert," Deryn sputtered. "You can't go to the machine room!"

Dr. Barlow took Tazza's leash from her. "That cargo is more important than your regulations, young man."

"But passengers are supposed to stay - "

"And midshipmen are supposed to be sixteen years old." Dr. Barlow waved her hand. "Don't you have some sort of battle station to get to?"

Deryn let out a pained growl, but gave up in disgust and turned away. She'd done her best - the lady boffin could hang herself out the windows if she wanted.

As Deryn ran back toward the main gondola, the aluminum walkway trembled under her feet. The whole crew was scrambling, filling the passageways of the ship. She dodged past a squad of men in gastric suits and reached the gut hatch, dropping halfway through for a peek outside.

The icy wind between gondola and airbeast rumbled with an unfamiliar sound. Not the hum of motivator engines - the angry snarl of Clanker technology. A winged shape caught a flash of moonlight in the distance, an Iron Cross painted on its tail.

The German aeroplanes could fly this high after all.

Deryn dropped the rest of the way down, landing hard enough to bang her teeth together. The middies' battle station was topside with the bats, so she'd need a flight suit to keep from freezing. Deryn's suit was back in her cabin, but the riggers always had spares hanging in their bunk room. She dodged through the press of men and hydrogen sniffers, looking for a suit with a pair of gloves stuffed into the pockets. There wasn't time to find goggles; Dr. Barlow's pigheadedness had delayed her long enough.

As she buttoned the coverall up to her neck, Deryn felt dizzy for a moment. The rush of battle had come too soon after the shock of Dr. Barlow's near discovery. The lady boffin had promised not to tell, but she didn't know the whole story - not yet. With those sharp eyes of hers, she'd have to guess the truth eventually.

Deryn took a deep breath and shook her head clear. This wasn't the time to fret about secrets. The war was finally here.

She gave her safety line a yank to test its strength, then headed for the rigging hatches.

There were at least a half dozen flying machines hunting the Leviathan. They were hard to count, staying in the distance to keep clear of the strafing hawks and their aeroplane nets.

Deryn was halfway to topside, climbing fast in the freezing wind. Men and fabricated animals swarmed the ratlines, the ropes pressing hard against the membrane with their weight.

She heard the motivator engines change pitch, and the world began to tilt. As the airship rolled, Deryn found herself on the underside again, hanging from the ratlines by two hands. The crewmen around her swung from their safety harnesses, but Deryn's clip dangled unused from her belt.

"Blisters!" she swore, looking up at her aching hands -  possibly Mr. Rigby had been right about using safety clips in battle.

She swung her feet, hooking one leg into the ropes to free a hand. The ship rolled harder over, and a message lizard overhead lost its grip. It tumbled past her, shouting random words in a dreadful mix of human voices.

Deryn tore her eyes away from the poor beastie - her fingers had found the safety clip. After snapping it onto a rope, she let herself hang from the harness, resting the burning muscles in her hands.

A roar was building in the air.

From half a mile away a Clanker machine rushed toward her. An engine thundered on each wing, billowing twin trails of smoke. The broad, batlike wings stretched and twisted as the aeroplane came alongside... .

Its machine gun erupted, sweeping the flank of the Leviathan.

Men and beasties scrambled to escape the path of the bullets. Deryn saw a hydrogen sniffer hit, dancing in agony against the ratlines, then flailing madly as it fell. Glowworms sputtered bright green sparks as they were torn apart beneath the skin.

The aeroplane kept coming, thundering straight toward her. Deryn unclipped her harness and slid down as fast as she could. Bullets rippled through the membrane just overhead, like stones splashing into water. The ropes jerked in her grasp, trembling with the airship's pain.

The gun finally sputtered out, the aeroplane peeling away. But a bright spark flared against the darkness. The gunner had ignited a phosphorous canister. He hoisted it high, the device sparking and smoking as the plane circled back toward the Leviathan.

Deryn's hands tightened on the ropes, but there was nowhere to climb. The bitter-almond scent of hydrogen filled her lungs. The entire airship was primed to explode.

But then a searchlight swept into view. An aerie of strafing hawks followed its arc, carrying an aeroplane net. Its glistening strands trailed from the birds' harnesses, binding them together in a web of gossamer.

The hawks turned and wheeled in formation, stretching the glowing lace across the aeroplane's path... .

The machine crashed into the net, which wrapped around it, spilling fabricated spider acid from its strands. The acid burned through wings and struts and flesh in seconds. Pieces spun off wildly, the plane's wings folding like scissors in the air.

The Clanker crewmen, the deadly phosphorous canister, and a hundred metal parts tumbled toward the snowy peaks below.

A ragged cheer went up along the airship's flank, fists raised as the machine fell. The riggers were soon at work patching the membrane, but a few men hung unmoving in their harnesses, lifeless or moaning in pain.

Deryn wasn't a medic, and she was supposed to be topside by now, but it took her a long moment to start climbing again and leave the bleeding crewmen behind.

There were more aeroplanes out there, she reminded herself, and the fl¨¦chette bats needed feeding.

Topside was covered with crewmen, guns, and sniffers going barmy with the smell of spilled hydrogen.

Deryn stayed off the crowded dorsal ridge, running along the soft membrane to one side. She reckoned the airbeast wouldn't notice one wee middy's footsteps after all those bullets ripping through its side.

The Leviathan's crew was firing back now, air guns chattering from the dorsal ridge and engine pods, searchlights guiding the strafing hawks out into the darkness. But what the ship really needed was more fl¨¦chette bats in the air.

When she reached the bow, Newkirk and Rigby were already there, wildly casting handfuls of feed. A few riggers had joined them to make up for the missing middies.

The bosun glared at her, and Deryn spat the words, "Tending to the boffin, sir!"

"Thought as much." He tossed her a feed bag. "They caught us napping, didn't they? Didn't know these blasted Clankers could fly so high!"

Deryn scooped out grain and fl¨¦chettes as fast as she could. Most of the bats were already airborne in all the ruckus.

"Get down, lads!" someone cried. "One's coming in!"

An aeroplane was roaring straight toward the bow. Deryn dropped, landing hard on a stray fl¨¦chette. The main air gun fired, and she felt the whoosh of bolts flying overhead. A host of startled bats streamed up in the bolts' wake.

Deryn glanced up. The air gun had hit home. The aeroplane shuddered, its engine coughing once. Then it twisted in the air and began to spin out of control, crumpling like paper in a giant hand.

Triumphant cries rose up across the airship's topside, but Mr. Rigby didn't pause to cheer. He scrambled to his feet and ran to Newkirk, snapping their safety lines together.

"Come on, Sharp!" he yelled. "Link up! We're going forward."

Deryn jumped up and ran after them, clipping her safety line to Newkirk's. The bosun led them off the dorsal ridge and onto the downward slope of the bow. The last few hundred bats always malingered in the nesting coves, and tonight the Leviathan needed all of her beasties in the air.

The bow skin was tougher than the flank, designed for plowing through storm fronts and squalls. Deryn's boots skidded on its hard surface, the heavy feed bag pulling her off balance. She swallowed - ropes and ratlines were few and far apart here on the airbeast's forehead.

The slope grew steeper. Soon Deryn could see all the way down to the blinders stretched across the whale's eyes, shielding them from distractions and the sting of bullets.

Another aeroplane roared beneath them, its machine gun firing at the port engine pod. The sound of shrieking gears rang in the cold air. In answer, two searchlight beams swept to follow the plane, full of dark and fluttering shapes... .

Deryn watched with horror. The searchlight crews weren't bothering to turn the beams red, the signal for the bats to release their fl¨¦chettes. They were guiding the flock straight into the path of the Clanker aircraft. The bats themselves weren't very heavy, but the metal spikes in their guts were enough to shred the aeroplane. The sickening shrieks of the poor wee creatures carried over the noise of ruined engines and tearing wings.

As Deryn watched the aircraft fall, her feet slipped. The ground was shifting beneath her.

"We're diving, lads!" Mr. Rigby shouted. "Get hold of something!"

Snow-covered mountains tilted into view ahead, and Deryn's stomach twisted. The airship had never dived this fast! Deryn dropped flat, fingers scrabbling for purchase. The feed bag skidded away, spilling figs and fl¨¦chettes into the night sky.

She was still sliding ... falling.

Then the safety line jerked, bringing Deryn to a halt. She looked up to see Newkirk and Rigby settled in a nesting cove, bats swirling around their heads.

She pulled herself up into the warmth of the cove. It was full of bat dung and old fl¨¦chettes, but there were plenty of handholds, at least.

"Glad you could join us, Mr. Sharp," Newkirk said, grinning like a loon. "This is brilliant, isn't it?"

Deryn frowned. "When did you get so brave?"

Before he could answer, the world rolled beneath them again.

"We've lost an engine," Mr. Rigby said.

Deryn closed her eyes, listening to the pulse of the airship. The ship sounded weak. It flew at an odd angle, the airflow turbulent around them.

Clanker aeroplanes still rumbled out there in the darkness - two of them, by the sound - and the Leviathan's searchlight beams looked almost empty of bats. The beasties were uselessly scattered across the night sky, too scared by gunfire and collisions to reform.

"We need more bats in the air!" Mr. Rigby shouted, and swiftly unwound a rope from his belt, replacing the line connecting Deryn and Newkirk with a fifty-foot length. "There's a big cove below us, Sharp. Swing down and see if you can scare up a few more of the little blighters." He shoved his own feed bag into her hands. "Make sure the beasties are stuffed before you boot them out."

"What about me?" Newkirk complained. Battle seemed to agree with him, but Deryn just felt airsick from it all.

"When I've got a longer line on you," Rigby said, still working his ropes. "Don't fancy losing my last two middies."

Deryn climbed over the edge of the cove, trying to ignore the mountain peaks rising steadily toward them. Had the airship lost too much hydrogen to stay aloft?

She forced the thoughts from her head, carefully making her way down toward a dark rift in the airbeast's skin. The growl of a Clanker engine was building in her ears, but Deryn didn't dare look away from her feet and hands.

Only a few more yards ...