"Bring along a vast fortune in gold? I should think that would be self-evident." Volger unlocked the case with a flick of the key, then opened it.

The gold bars shone dully, a dozen of them - more than two hundred kilograms. Volger lifted a bar with both hands, grunting as he hurled it through the window. They both leaned forward, watching it flash in the sunlight as it fell.

"Well, that's seventy thousand kroner gone," Volger said.

Alek bent and lifted one, the muscles in his hands screaming as he heaved it up and out. "You almost got us all killed! Are you mad?"

"Mad?" Volger grunted, lifting another bar. "For trying to save what little of your inheritance you haven't already thrown away?"

"This is an airship, Volger. Every gram makes a difference!" Alek pulled another bar from the case. "And you bring gold bullion aboard?"

"I didn't think the Darwinists would cut it so close." Volger grunted again, another gold bar spinning away. "And just imagine how pleased you'd have been if I'd been right."

Alek groaned. Working alongside the Leviathan's crew, he had absorbed the airmen's mania about weight. But Volger thought in terms of heavy cannon and armored walkers.

Alek pushed another bar through the window - only six left.

"But we may as well finish the job," Volger said. "Throw it all out, like the walker and the castle and ten years' worth of supplies!"

"So that's what this is about?" Alek said, lifting another bar. "That I've thrown away all your hard work? Don't you realize we've gained something more important?"

"What could be more important than your birthright?"

"Allies." Alek pushed the gold bar out the window. As it fell, he thought he felt the deck leveling beneath him. Maybe this was working.

"Allies?" Volger snorted, then lifted another bar and flung it out. "So your new friends are worth throwing away everything your father left you?"

"Not everything," Alek said. "All my life you and my father prepared me for this war. Thanks to that, I don't have to hide from it. Come on, there are only four left. The two of us can lift them all at once."

"Still too heavy." Volger shook his head. "Your father was an idealist and a romantic, and it cost him dearly. I always hoped you'd inherited a bit of your mother's pragmatism."

Alek looked down at the case.

Only four gold bars... . He wondered what a boy like Dylan would say to such a fortune. Maybe it wasn't entirely mad, what Volger had done.

"Well," he said, "perhaps we could save one."

Volger smiled as he knelt, pulling one of the bars out and sliding it back under the bed. "There may be hope for you after all, Alek. Shall we?"

Alek knelt across from him, and together they heaved the case up, Volger's face turning red with the effort. Alek felt his own muscles throbbing in his arms.

Finally the case was resting on the windowsill. Alek took a step back, then threw himself against the case as hard as he could.

The last three bars spilled out as they fell toward the snow, spinning wildly and glittering with sunlight. Alek felt Volger's grip on his shoulder, as if the man thought he would go tumbling after them. The airship pitched up beneath Alek's feet, rolling to starboard as the weight of his father's gold fell away.

"But I truly didn't think it would matter, not on a ship this huge," Volger said quietly. "I never meant to endanger you."

"JETTISONING THE LAST INGOTS."

"I know that," Alek sighed. "Everything you've done has been to protect me. But I've chosen a different path now - one less safe. Either you recognize that or we part ways when this ship lands."

Count Volger took a deep, slow breath, then bowed. "I remain at your service, Your Serene Highness."

Alek rolled his eyes, and started to say more. But a light flickered outside, and they both leaned out the window again.

Flares were arcing up from the ground. The Leviathan had reached the first German scouts. Their mortars were firing, sending bright cinders aloft. Alek breathed in the sharp, familiar scent of phosphorous, and the rumble of nearby cannon reached his ears.

"I just hope we weren't too late."

THIRTY-NINE

"Off your bums, beasties!" Deryn shouted, sending another cluster of bats fluttering into the air.

Mr. Rigby had sent the middies forward to lighten the bow. Something heavy was holding the airship's nose down. Either that or the forward hydrogen cells were leaking like mad. But the sniffers hadn't found the slightest rip.

From up here Deryn could see the whole valley, and the view was barking dire. The Clanker walking machine had come to a halt a few miles away. Its scouts stretched in a line across the glacier, waiting for the airship to fly into their guns.

Suddenly the membrane reared beneath Deryn's feet. The nose had tipped up a bit.

"Did you feel that?" Newkirk yelled from across the bow.

"Aye, something's working," she called back. "Keep rousting the beasties!"

Deryn unclipped her safety line and ran toward another cluster of bats, shouting and waving her arms. They turned to stare at her skeptically before scampering - they hadn't been fed their fl¨¦chettes yet.

And they wouldn't be anytime soon. When the ballast alert had sounded, Mr. Rigby had tossed two whole bags of spikes over the side. If the zeppelins caught up, the Leviathan would be defenseless, her flocks stuffed with plenty of food - but no metal - and now scattered to the winds.

At least the borrowed Clanker engines were working, so far. They were noisy and smelly, and threw out enough sparks to give Deryn the mortal shivers, but blisters could they push the ship along!

The old motivator engines had only nudged the airbeast in the right direction, like a plowman flicking a donkey's ears. But now that was upside down: The cilia were acting like a rudder, setting the course while the Clanker engines propelled the ship.

Deryn hadn't realized the whale could be such a clever-boots, adapting to the new engines so quickly. And she'd never seen an airship move this fast. The pursuing zeppelins - some of them small, nippy interceptors -  were already falling behind.

But the German land machines still waited dead ahead.

The ship bucked again, and Deryn lost her footing, skidding down the slope. Her foot caught in a ratline, jerking her to a nasty halt.

"Safety first, Mr. Sharp!" Newkirk called, snapping the shoulder straps of his harness like suspenders.

"Pretty smug, for a bum-rag," Deryn muttered, snapping her clip back onto a ratline. She gave the bats another halfhearted shout, but the ship didn't seem to need it anymore. The airbeast's nose was pulling up in starts, another jolt skyward coming every ten seconds or so.

It felt as if they were chucking officers out the bridge front window! But at least the ship was climbing.

Deryn eased forward a bit, until she had a good view of the Germans.

The little scout craft, skittering machines like metal daddy longlegs, were shooting off their mortars. But the barrage was only flares, which weren't designed to climb very high. They arced a few hundred feet up and burned there uselessly, singeing the air beneath the gondola's belly.

But now the big eight-legged walker's guns were elevating, tracking the airship but holding their fire. At the speed the Leviathan was making, they'd only get one shot before she flew past them.

A command whistle began to scream, one long note, pitched almost too high to hear. The all-hands-aft signal!

Deryn turned and ran. On either side of her, sniffers scuttled along the membrane, headed toward the tail. The spine was crowded with men and beasts all running in the same direction, the air gun crews pulling up their weapons to carry them along.

It was a last, desperate attempt to move every squick of weight to the rear of the ship. Done all at once, it would tip the ship's nose up, driving her still higher into the air.

Halfway back, Deryn saw flickers on the snow below, and glanced over her shoulder. The muzzles of the walker's guns were blazing, smoke billowing out in clouds.

Before the rumble even reached her ears, the airship bucked again - harder this time, as if someone had tossed a grand piano overboard. The nose flew up, hiding Deryn's view of the German walker, and the deck rolled hard to starboard. Whatever they'd tossed away, it had been on the port side.

She heard the tardy thunder of the guns then, and shells started arcing past. They were huge incendiaries, igniting the sky like gouts of frozen lightning.

One flew past so near that Deryn felt its heat on her cheeks and forehead. The air was instantly burned dry, her eyes forced half shut by the shell's fury. The light from the flaming missiles threw the shadows of men and beasts across the membrane, stretched and misshapen by the airship's curves.

But the entire barrage was flying too far to port.

The sudden loss of weight, whatever it had been, had rolled the airship out of the way just in time. And the riggers' work over the last few days had held - not a squick of hydrogen was flaring from the skin.

But Deryn kept running for the ship's tail, as did the rest of the topside crew. Not just to pull the ship up harder, but to see behind them.

There it was again, the eight-legged walker, now sliding into the distance astern. Its guns were swiveling, trying to spin around and fire once more. But the Leviathan's new Clanker engines were carrying her away too fast.

By the time the guns blazed again, the burning shells fell hundreds of feet short. They dropped into the snow and expended their anger there, the walking machines vanishing behind a veil of steam.

Deryn joined the cheer that rose up along the spine. The hydrogen sniffers howled along, half mad from all the ruckus.

Newkirk appeared, panting and covered with sweat, and clapped her on the shoulder. "Blistering good fight! Eh, Mr. Sharp?"

"Aye, it was. I just hope it's over."

She raised her field glasses to gander at the zeppelins, now silhouetted by the setting sun. They'd fallen still farther behind, hopelessly outmatched by the Stormwalker engines.

"They'll never catch up now," she said. "Not with night falling."

"THE HERKULES' SHELLS GO WIDE."

"But I thought those Predators were fast!"

"Aye, they are. But we're faster, now that we've got those engines on us."

"But haven't they got Clanker engines too?" Newkirk asked.

Deryn frowned, looking down at the Leviathan's flanks. The cilia were stirring madly, weaving the airflow around the ship, somehow adding the currents of the sky to the raw power of the engines.

"We're something different now," she said. "A little of us and a little of them."

Newkirk thought a moment, then hmphed and clapped her on the back again. "Well, frankly, Mr. Sharp, I don't care if the kaiser himself gives us a push, as long as it gets us clear of this iceberg."

"Glacier," Deryn said. "But you're right - it's good to be flying again."

She closed her eyes and took a deep breath of freezing air, feeling the strange new thrum of the membrane beneath her boots.

Already, her air sense told her, the beast was veering south, setting course for the Mediterranean. The zeppelins behind were an afterthought; the Ottoman Empire lay ahead.

Whatever sort of tangled crossbreed the Clankers had made her into, the Leviathan had survived.

FORTY

The pistons were the trickiest bits to draw. There was something about the way they fit together - the Clanker logic of them - that blistered Deryn's brain.

She'd been sketching the new engines all afternoon, imagining the drawings in some future edition of the Manual of Aeronautics. But even if no one ever saw them, the warm day was excuse enough for lounging here. The airship was only a hundred yards above the water, the afternoon sun bouncing from the waves and setting everything aglitter. After three nights shipwrecked on a glacier, it seemed the perfect afternoon to lie in the ratlines, soak up the heat, and draw.

But even with the Mediterranean Sea stretching out in all directions, the Clankers never seemed to relax. Alek and Klopp had been busy down on the pods since noon, fashioning windshields to protect the engine pilots. That's what they were calling themselves - pilots, not engine men or any proper Air Service term. They'd already forgotten that the real pilots were on the bridge.

Then again, she'd heard it rumored that the ship didn't need pilots these days, Darwinist or Clanker. The whale had developed an independent streak, a tendency to choose its own way among the thermals and updrafts. Some of the crew wondered if the wreck had rattled the beastie's attic. But Deryn reckoned it was the new engines. Who wouldn't feel feisty with all that power?

A bee was crawling across her sketch pad, and she waved it away. The hives had come out of their three-day hibernation hungry, gorging themselves on the wildflowers of Italy as the Leviathan headed south. The strafing hawks looked fat and happy this afternoon, full of wild hares and stolen piglets.

"Mr. Sharp?" came the master coxswain's voice.

Deryn almost snapped to attention. But then she saw the message lizard staring at her, its beady eyes blinking.

"Please report to the captain's quarters," the lizard continued. "Without delay."

"Aye, sir. Right away!" Deryn winced as she heard her voice squeak like a girl's. She lowered it and said, "End message."

Gathering her pad and pencils as the beastie scampered away, Deryn wondered what she'd done wrong. Nothing bad enough to earn an audience with the captain - not that she could remember. Mr. Rigby had even commended her on taking Alek hostage during the Stormwalker attack.

But her nerves were twitching nonetheless.

The captain's quarters were up near the bow, next to the navigation room. The door was half open and Captain Hobbes sat behind his desk, the wall charts rustling in the warm breeze from an open window.

Deryn saluted smartly. "Midshipman Sharp reporting, sir."

"At ease, Mr. Sharp," the man said, which only made her more nervous. "Please come in. And shut the door."

"Aye, sir," she said. The captain's door was a solid piece of natural wood, not fabricated balsa, and it thumped shut with a heavy finality.

"May I ask you, Mr. Sharp, your opinion of our guests?"

"The Clankers, sir?" Deryn frowned. "They're ... very clever. And quite determined about keeping those engines running. Good allies to have, I'd say."

"Would you? Then it's lucky they aren't officially our enemies." The captain tapped his pencil against the cage that sat on his desk. The carrier tern inside it fluttered, its tongue slipping out to taste the air. "I've just learned that England is not at war with Austria-Hungary, not yet. At the moment we need only concern ourselves with the Germans."

"Well, that's handy, sir."

"Indeed." The captain leaned back and smiled. "You're rather friendly with young Alek, aren't you?"

"Aye, sir. He's a good lad."

"So he seems. A young boy like that needs friends, especially having run away from home and country." The captain lifted an eyebrow. "Sad, isn't it?"

Deryn nodded, saying carefully, "I suppose so, sir."

"And all quite mysterious. Here we are at their mercy, mechanically speaking, and yet we don't know much about Alek and his friends. Who are they, really?"

"They are a bit cagey, sir," Deryn said, which wasn't a lie.

"THE CAPTAIN'S QUARTERS."

"Quite so." Captain Hobbes picked up the piece of paper before him. "The First Lord of the Admiralty himself has become curious about them, and requests that we keep him informed. So it might be useful, Dylan, if you kept your ears open."

Deryn let out a slow breath.

This was the moment, of course, when duty required her to tell the captain all she knew - that Alek was the son of Archduke Ferdinand, and that the Germans were behind his father's murder. Alek had said it himself: This wasn't just family business. The assassinations had started the whole barking war, after all.

And now Lord Churchill himself was asking about it!

But she'd promised Alek not to tell. Deryn owed him that much, after setting the sniffers on him the first time they'd met.

For that matter, the whole barking ship owed him a debt. Alek had revealed his hiding place to help them fight the zeppelins, giving up his Stormwalker and a castle full of stores. And all he'd asked in return was to stay anonymous. It seemed impolite for the captain even to be asking.

She couldn't break her promise - not like this, without even talking to Alek first.

Deryn saluted smartly. "I'm happy to do whatever I can, sir."

And she left without telling the captain any of it.

That evening when she went to find Alek on egg duty, the machine room was locked.

Deryn gave the door a couple of loud raps. Alek opened it and smiled, but he didn't stand aside.

"Dylan! Good to see you." He lowered his voice. "But I can't let you in."

"Why not?"

"One of the eggs is looking pale, so we've had to rearrange the heaters. It's all very complicated. Dr. Barlow said that another person in the room could affect the temperature."

Deryn rolled her eyes. As Constantinople drew closer, the lady boffin grew more and more protective of her eggs. They'd survived an airship crash, three nights on a glacier, and a zeppelin attack, and yet she seemed to think they'd shatter if anyone looked at them sideways.

"That's a load of yackum, Alek. Let me in."

"Are you sure?"

"Yes! We're keeping them close enough to body temperature. Another person in there won't hurt."

Alek hesitated. "Well, she also said that Tazza hasn't had a walk all day. He'll be tearing down the walls of her cabin if you don't see to him."

Deryn sighed. It was amazing how the lady boffin could be so tiresome without even being in the room.

"I've got something important to tell you, Alek. Shove aside and let me in!"

He frowned but relented, letting her squeeze past into the sweltering machine room.

"Blisters, are you sure it's not too hot in here?"

Alek shrugged. "Dr. Barlow's orders. She said the sick one needed to be kept warm."

Deryn looked at the cargo box. Two of the surviving eggs were nestled together at one end; the other was alone in the middle, surrounded by a pile of glowing heaters -  far too many. She took a step forward to check the thermometer, then frowned. They were Dr. Barlow's barking eggs. If she wanted to cook them, fine.

Deryn had more important things to worry about.

She turned to Alek. "The captain called for me today. He asked about you."

Alek's face darkened. "Oh."

"Don't worry. I didn't tell him anything," she said. "I mean, I wouldn't break my promise."

"Thank you, Dylan."

"Even though he ..." She cleared her throat, trying to sound casual. "He told me to keep an eye on you, and said I should tell him anything I find out."

Alek nodded slowly. "He gave you a direct order, didn't he?"

Deryn opened her mouth, but no words came out - something was shifting inside her. On her way here she'd hoped Alek would give her permission to tell the captain, solving the whole dilemma. But now an entirely different desire was creeping into her mind.

What she really wanted, Deryn realized, was for Alek to know that she'd lied for him, that she would go on lying for him.

She suddenly had that feeling again, the same as when Alek had told her his parents' story - a crackling in the overheated air. Her skin tingled where he'd hugged her.

This wasn't going right at all.

"Aye. I suppose he did."

Alek sighed. "A direct order. So if they find out you've hidden my identity, they'll hang you as a traitor."

"Hang me?"

"Yes, for consorting with the enemy."

Deryn frowned. In all her weighing of promises and loyalties, she hadn't thought that far ahead. "Well ... not quite the enemy. We're not at war with Austria, the captain says."

"Not yet. But from what Volger's heard on the wireless, it'll only be a week or so." He smiled sadly. "Funny, all those politicians trying to decide if we're enemies or not."

"Aye, barking hilarious," Deryn murmured. She was the one standing here, not some politician. This was her decision. "I promised, Alek."

"But you also took an oath to the Air Service, and to King George," he reminded her. "I'm not going to make you break that oath. You're too good a soldier for that, Dylan."

She swallowed, shifting on her feet. "But what will they do to you?"

"I'll be locked up tight," Alek said. "I'm too valuable to let escape into the wilds of the Ottoman Empire. And when we get back to England, they'll put me somewhere safe until the war's over."

"Blisters," she said. "But you saved us!"

The boy shrugged. The sadness was still in his eyes. Not brimming over into tears again, but deeper than she'd ever seen it.

She was taking his one squick of hope away.

"I won't tell," she promised again.

"Then I'll have to give myself up," Alek said sadly. "The truth has to come out sooner or later. No point in you getting yourself hanged."

Deryn wanted to argue, but Alek wasn't making it easy. He was right about disobeying orders in wartime. It was treason, and traitors were executed.

"This is all Dr. Barlow's fault," she grumbled. "I wouldn't have found out who you were if she weren't so nosy. She's not telling either, but of course they'd never hang a clever-boots like her."

"No, I suppose not." Alek shrugged again. "She's not a soldier, after all. On top of which, she's a woman."

Deryn's mouth dropped open. She'd almost forgotten -  the Air Service wouldn't hang a woman, would they? Not even a common soldier. They'd boot her out, certainly, take away everything she'd ever wanted - her home on this airship, the sky itself. But they'd never execute a fifteen-year-old girl. It would be too barking embarrassing.

She felt a smile on her face. "Don't worry about me, Alek. I've got a trick up my sleeve."

"Don't be stupid, Dylan. This isn't one of your madcap adventures. This is serious!"

"My adventures are all barking serious!"

"But I can't let you take the risk," he pleaded. "Enough people have died because of me already. I'll go with you to the captain now and explain everything."

"You don't have to," Deryn argued, but she knew Alek wouldn't listen. He wouldn't believe she was safe from hanging unless he knew the truth. Strangest of all, she almost wanted to tell him, to trade her secret for his.

She took a step closer.

"They won't hang me, Alek. I'm not the soldier you think I am."

He frowned. "What do you mean?"

Deryn took a deep breath. "I'm not really a - "

A sound came from the door - the jangling of keys. It opened and Dr. Barlow strode in, her eyes darkening as they fell on Deryn.

"Mr. Sharp. What are you doing here?"

FORTY-ONE

Alek had never seen such a cold look on Dr. Barlow's face. Her eyes flicked from Dylan to the eggs, as if she thought the boy had come to steal one.

"Sorry, ma'am," Dylan muttered, swallowing whatever he'd been about to say. "I was just heading up to see Tazza."

Alek grabbed his arm. "Wait. Don't go." He turned to Dr. Barlow. "We have to tell the captain who I am."

"And why would we do that?"

"He's ordered Dylan to keep an eye on me, and to tell him everything he learns. Everything." Alek stood up straighter, trying to summon his father's voice of command. "We can't ask Dylan to disobey a direct order."

"Don't worry about the captain." Dr. Barlow waved her hand. "This is my mission, not his."

"Aye, ma'am, but it's not just him," Dylan said. "The Admiralty knows we've got Clankers aboard, and the First Lord himself was asking about them!"

Dr. Barlow's face darkened again, and her voice dropped to a growl. "That man. I should have known. This crisis is all his fault, and yet he still dares to interfere with my mission!"

Dylan tried to sputter some response to this, but failed.

Alek frowned. "Who is this fellow?"

"She's speaking of Lord Churchill," Dylan managed. "He's the First Lord of the Admiralty. He runs the whole barking navy!"

"Yes, and you'd think that would be enough for Winston. But now he's gone beyond his station," Dr. Barlow said. She took a seat beside the eggs, pulling a few of the heaters away from the sick one. "Sit down, both of you. You may as well know the whole story, as the Ottomans will find out soon enough."

Alek shared a look with Dylan, and they both settled onto the floor.

"Last year," she began, "the Ottoman Empire offered to buy a warship being built in Britain. It is among the most advanced in the world, with a companion creature strong enough to change the balance of power on the seas. And it is ready to sail."

She paused, peered at a thermometer, then moved a few more heaters around in the straw.

"But the day before you and I met in Regent's Park, Mr. Sharp, Lord Churchill decided to seize that ship for Britain. Even though it was already paid for in full." She shook her head. "He suspected that the Ottomans might wind up on the other side in this war, and he didn't want the Osman in enemy hands."

Alek frowned. "Well, that's just plain thievery!"

"I suppose so." Dr. Barlow flicked a piece of straw. "More important, it was a shocking bit of diplomacy. That annoying man has made it nearly certain that the Ottomans will join the Clankers. It is our mission to prevent that from happening."

She patted the sick egg.

"But what's that got to do with my secret?" Alek asked.

Dr. Barlow sighed. "Winston and I have been at odds about the Ottomans for some time. He doesn't appreciate that I'm trying to fix his mistakes, and he'd love to get in my way." She looked at Alek. "Finding out that we have the son of the Archduke Ferdinand as our captive would provide him with an excuse to turn this ship around."

Alek set his teeth. "A captive? Our countries aren't even at war! And may I remind you who runs the engines for this ship?"

"That is precisely my point," Dr. Barlow said. "Now do you see why I don't want you and Dylan blabbing to the captain? It would cause a great deal of trouble, setting us all against one another. And we've been getting along so splendidly!"

"Aye, she's right," Dylan said. The boy looked relieved.

Dr. Barlow turned and adjusted the egg again. "You can leave Lord Churchill to me."

"But it's not just your problem, ma'am," Alek said. "It's Dylan's as well. You say you'll protect him, but how can you promise to ..." He frowned. "Who exactly are you, madam, to take on this Lord Churchill?"

The woman rose to her full height, adjusting her bowler hat.

"I am exactly as you see me - Nora Darwin Barlow, head keeper of the London Zoo."

Alek blinked. Had she said Nora Darwin Barlow? A new trickle of nerves began to grow in his stomach.

"You m-mean," Dylan stammered, "your grandfather ... the barking beekeeper?"

"I never said he was a beekeeper," she laughed. "Only that he found bees inspiring. His theories wouldn't have achieved nearly such elegance without their instructive example. So stop your worrying about Lord Winston, Mr. Sharp. He's nothing I can't handle."

Dylan nodded, looking pale. "I'll just go see to Tazza, then, ma'am."

"An excellent idea." She opened the door for him. "And don't let me catch you here again without permission."

The boy started to slip out the door, then cast Alek one last look. For a moment their eyes locked. Then Dylan shook his head and disappeared.

He was probably as astonished as Alek. Dr. Barlow wasn't just a Darwinist; she was a Darwin - the granddaughter of the man who'd fathomed the very threads of life.

Alek felt the floor shifting beneath him, but he doubted it was the airship turning. He was standing beside the incarnation of everything he'd been taught to fear.

And he had entrusted himself to her completely.

Dr. Barlow turned back to the eggs. She was rearranging the heaters, stacking them near the sick egg again.

Alek clenched his fists to keep the quaver from his voice.

"But what about when we get to Constantinople?" he said. "Once you and your cargo are safely there, what's to stop you from locking me up?"

"Please, Alek. I have no intention of locking anyone up." She reached out to ruffle his hair, which sent a shiver down his spine. "I have other plans for you."

She smiled as she walked to the door.

"Trust me, Alek. And do keep a close eye on those eggs tonight."

As the door closed behind her, Alek turned to look at the softly glowing cargo box, wondering what was in the eggs that was so important. What sort of fabricated creature could replace a mighty warship? How could a beast no bigger than a top hat keep an empire out of this war?

"What's inside you?" Alek said softly.

But the eggs just sat there, not answering at all.

AFTERWORD

Leviathan is a novel of alternate history, so most of its characters, creatures, and mechanisms are my own inventions. But the book's time line is based on the actual summer of 1914, when Europe found itself lurching toward a disastrous war. So here's a quick review of what's true and what's fictional in the story so far.

On June 28, Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, and his wife, Sophie Chotek, were assassinated by young Serbian revolutionaries. In my world they survived a first pair of attacks, but were poisoned later that evening. In the real world, however, they were killed in the afternoon. (I wanted my book to start at night.) Just as in Leviathan, the assassinations led to war between Austria and Serbia, which spread to Germany and Russia, and so on. By the first week of August the globe was embroiled in the Great War - now called World War I. These two tragic deaths, and some appalling diplomacy among the great powers of Europe, resulted in millions more.

There were rumors at the time that the Austrian government, or perhaps that of Germany, had secretly arranged the murders - either as an excuse to start a war or because Franz Ferdinand was too peace-minded. Few historians believe this conspiracy theory now, but it took decades to be disproved. Certainly the German military was determined to get a war started, and used the assassinations to do exactly that.

Franz and Sophie had no son called Aleksandar, though. Their children were named Sophie, Maximilian, and Ernst. But just like Alek in my story, these three were forbidden to inherit Franz's land or titles, all thanks to their mother's less-than-royal blood. And, just as in Leviathan, their parents had implored both the Austro-Hungarian emperor and the pope to change this situation. In the real world, though, Franz and Sophie did not prevail.

The romantic story that Alek tells about the tennis game and the pocket watch is entirely true.

Charles Darwin really did exist, of course, and in the mid-1800s made the discoveries that are at the core of modern biology. In the world of Leviathan he also managed to discover DNA, and learned to reach into these "life threads" to create new species. In our own world the role of DNA in evolution wasn't fully understood until the 1950s, however. We are only now fabricating new life forms, and none so grand as Deryn Sharp's airship home.

Nora Darwin Barlow was also a real person, a scientist in her own right. The columbine Nora Barlow flower is named after her, and she also edited many definitive editions of her grandfather's work. But she was neither a zoo-keeper nor a diplomat.

The Tasmanian tiger is an entirely real beast. You could have seen a thylacine much like Tazza at the London Zoo in 1914, but no longer. Despite having been the top predator of the Australian continent only a few thousand years ago, the species was hunted to extinction by humans in the early twentieth century.

The last known Tasmanian tiger died in captivity in 1936.

As for the Clankers' inventions, they are somewhat ahead of their time. The first real armored fighting machines didn't enter battle until 1916. They couldn't walk, but used tractor treads, just as tanks do today. The world's militaries are only now beginning to develop useful vehicles with legs instead of treads or wheels. Animals are still much better at walking over rough terrain than any machine.

So Leviathan is as much about possible futures as alternate pasts. It looks ahead to when machines will look like living creatures, and living creatures can be fabricated like machines. And yet the setting also recalls an earlier time in which the world was divided into aristocrats and commoners, and women in most countries couldn't join the armed forces - or even vote.

That's the nature of steampunk, blending future and past.

The conflict between Winston Churchill and the Ottomans over seized warships is also based in fact. But that is best left to the second book, which follows the Leviathan to the ancient city of Constantinople, capital of the Ottoman Empire.