'Siberia,' Alek said. The word slipped cold and hard from his tongue, as forbidding as the landscape passing below.

'We won’t be over Siberia till tomorrow.' Dylan sat at the table, still attacking his breakfast. 'And it’ll take almost a week to cross it. Russia is barking big.'

'And cold,' Newkirk added. He stood next to Alek at the window of the middies’ mess, both hands wrapped around a cup of tea.

'Cold,' repeated Bovril. The creature clutched Alek’s shoulder a little tighter, and a shiver went through its body.

In early October no snow lay on the ground below. But the sky was an icy, cloudless blue. The window had a lace of frost around its edges, left over from a frigid night.

Another week of flying across this wasteland, Alek thought. Farther from Europe and the war, and from his destiny. The Leviathan was still headed east, probably toward the empire of Japan, though no one would confirm their destination. Even though he’d helped the British cause back in Istanbul, the airship’s officers still saw Alek and his men as little better than prisoners. He was a Clanker prince and they were Darwinists, and the Great War between the two technologies was spreading faster every day.

'It’ll get much colder as we angle north,' Dylan said around a mouthful of his breakfast. 'You should both finish your potatoes. They’ll keep you warm.'

Alek turned. 'But we’re already north of Tokyo. Why go out of our way?'

'We’re dead on course,' Dylan said. 'Mr. Rigby made us plot a great circle route last week, and it took us all the way up to Omsk.'

'A great circle route?'

'It’s a navigator’s trick,' Newkirk explained. He breathed on the window glass before him, then drew an upside-down smile with one fingertip. 'The earth is round, but paper is flat, right? So a straight course looks curved when you draw it on a map. You always wind up going farther north than you’d think.'

'Except below the equator,' Dylan added. 'Then it’s the other way round.'

Bovril chuckled, as if great circle routes were quite amusing. But Alek hadn’t followed a word of it-not that he’d expected to.

It was maddening. Two weeks ago he’d helped lead a revolution against the Ottoman sultan, ruler of an ancient empire. The rebels had welcomed Alek’s counsel, his piloting skills, and his gold. And together they’d won.

But here aboard the Leviathan he was deadweight-a waste of hydrogen, as the crew called anything useless. He might spend his days beside Dylan and Newkirk, but he was no midshipman. He couldn’t take a sextant reading, tie a decent knot, or estimate the ship’s altitude.

Worst of all, Alek was no longer needed in the engine pods. In the month he’d been plotting revolution in Istanbul, the Darwinist engineers had learned a lot about Clanker mechaniks. Hoffman and Klopp were no longer called up to help with the engines, so there was hardly any need for a translator.

Since the first time he’d come aboard, Alek had dreamed of somehow serving on the Leviathan. But everything he could offer-walker piloting, fencing, speaking six languages, and being a grandnephew of an emperor-seemed to be worthless on an airship. He was no doubt more valuable as a young prince who had famously switched sides than as an airman.

It was as if everyone were trying to make him a waste of hydrogen.

Then Alek remembered a saying of his father’s: The only way to remedy ignorance is to admit it.

He took a slow breath. 'I’m aware that the earth is round, Mr. Newkirk. But I still don’t understand this ‘great circle route’ business.'

'It’s dead easy to see if you’ve got a globe in front of you,' Dylan said, pushing away his plate. 'There’s one in the navigation room. We’ll sneak in sometime when the officers aren’t there.'

'That would be most agreeable.' Alek turned back to the window and clasped his hands behind his back.

'It’s nothing to be ashamed of, Prince Aleksandar,' Newkirk said. 'Still takes me ages to plot a proper course. Not like Mr. Sharp here, knowing all about sextants before he even joined the Service.'

'Not all of us are lucky enough to have an airman for a father,' Alek said.

'Father?' Newkirk turned from the window, frowning. 'Wasn’t that your uncle, Mr. Sharp?'

Bovril made a soft noise, sinking its tiny claws into Alek’s shoulder. Dylan said nothing, though. He seldom spoke of his father, who had burned to death in front of the boy’s eyes. The accident still haunted Dylan, and fire was the only thing that frightened him.

Alek cursed himself as a Dummkopf, wondering why he’d mentioned the man. Was he angry at Dylan for always being so good at everything?

He was about to apologize when Bovril shifted again, leaning forward to stare out the window.

'Beastie,' the perspicacious loris said.

A black fleck had glided into view, wheeling across the empty blue sky. It was a huge bird, much bigger than the falcons that had circled the airship in the mountains a few days before. It had the size and claws of a predator, but its shape was unlike any Alek had seen before.

It was headed straight for the ship.

'Does that bird look odd to you, Mr. Newkirk?'

Newkirk turned back to the window and raised his field glasses, which were still around his neck from the morning watch.

'Aye,' he said a moment later. 'I think it’s an imperial eagle!'

There was a hasty scrape of chair legs from behind them. Dylan appeared at the window, shielding his eyes with both hands.

'Blisters, you’re right-two heads! But imperials only carry messages from the czar himself. . . .'

Alek glanced at Dylan, wondering if he’d heard right. Two heads?

The eagle soared closer, flashing past the window in a blur of black feathers, a glint of gold from its harness catching the morning sun. Bovril broke into maniacal laughter at its passage.

'It’s headed for the bridge, right?' Alek asked.

'Aye.' Newkirk lowered his field glasses. 'Important messages go straight to the captain.'

A bit of hope pried its way into Alek’s dark mood. The Russians were allies of the British, fellow Darwinists who fabricated mammothines and giant fighting bears. What if the czar needed help against the Clanker armies and this was a summons to turn the ship around? Even fighting on the icy Russian front would be better than wasting time in this wilderness.

'I need to know what that message says.'

Newkirk snorted. 'Why don’t you go and ask the captain, then?'

'Aye,' Dylan said. 'And while you’re at it, ask him to give me a warmer cabin.'

'What can it hurt?' Alek said. 'He hasn’t thrown me into the brig yet.'

When Alek had returned to the Leviathan two weeks ago, he’d half expected to be put in chains for escaping from the ship. But the ship’s officers had treated him with respect.

Perhaps it wasn’t so bad, everyone finally knowing he was the son of the late Archduke Ferdinand, and not just some Austrian noble trying to escape the war.

'What’s a good excuse to pay the bridge a visit?' he asked.

'No need for excuses,' Newkirk said. 'That bird’s flown all the way from Saint Petersburg. They’ll call us to come and fetch it for a rest and a feeding.'

'And you’ve never seen the rookery, your princeliness,' Dylan added. 'Might as well tag along.'

'Thank you, Mr. Sharp,' Alek said, smiling. 'I would like that.'

Dylan returned to the table and his precious potatoes, perhaps grateful that the talk of his father had been interrupted. Alek decided he would apologize before the day was out.

Ten minutes later a message lizard popped its head from a tube on the ceiling in the middies’ mess. It said in the master coxswain’s voice, 'Mr. Sharp, please come to the bridge. Mr. Newkirk, report to the cargo deck.'

The three of them scrambled for the door.

'Cargo deck?' Newkirk said. 'What in blazes is that about?'

'Maybe they want you to inventory the stocks again,' Dylan said. 'This trip might have just got longer.'

Alek frowned. Would 'longer' mean turning back toward Europe, or heading still farther away?

As the three made their way toward the bridge, he sensed the ship stirring around them. No alert had sounded, but the crew was bustling. When Newkirk peeled off to descend the central stairway, a squad of riggers in flight suits went storming past, also headed down.

'Where in blazes are they going?' Alek asked. Riggers always worked topside, in the ropes that held the ship’s huge hydrogen membrane.

'A dead good question,' Dylan said. 'The czar’s message seems to have turned us upside down.'

The bridge had a guard posted at the door, and a dozen message lizards clung to the ceiling, waiting for orders to be dispatched. There was a sharp edge to the usual thrum of men and creatures and machines. Bovril shifted on Alek’s shoulder, and he felt the engines change pitch through the soles of his boots-the ship was coming to full-ahead.

Up at the ship’s master wheel, the officers were huddled around the captain, who held an ornate scroll. Dr. Barlow was among the group, her own loris on her shoulder, her pet thylacine, Tazza, sitting at her side.

A squawk came from Alek’s right, and he turned to find himself face-to-face with the most astonishing creature. . . .

The imperial eagle was too large to fit into the bridge’s messenger cage, and it perched instead on the signals table. It shifted from one taloned claw to the other, glossy black wings fluttering.

And what Dylan had said was true. The creature had two heads, and two necks, of course, coiled around each other like a pair of black feathered snakes. As Alek watched in horror, one head snapped at the other, a bright red tongue slithering from its mouth.

'God’s wounds,' he breathed.

'Like we told you,' Dylan said. 'It’s an imperial eagle.'

'It’s an abomination, you mean.' Sometimes the Darwinists’ creatures seemed to have been fabricated not for their usefulness, but simply to be horrific.

Dylan shrugged. 'It’s just a two-headed bird, like on the czar’s crest.'

'Yes, of course,' Alek sputtered. 'But that’s meant to be symbolic.'

'Aye, this beastie’s symbolic. It’s just breathing as well.'

'Prince Aleksandar, good morning.' Dr. Barlow had left the group of officers and crossed the bridge, the czar’s scroll in her hand. 'I see you’ve met our visitor. Quite a fine example of Russian fabrication, is it not?'

'Good morning, madam.' Alek bowed. 'I’m not sure what this creature is a fine example of, only that I find it a bit . . .' He swallowed, watching Dylan slip on a pair of thick falconer’s gloves.

'Literal-minded?' Dr. Barlow chuckled softly. 'I suppose, but Czar Nicholas does enjoy his pets.'

'Pets, fah!' her loris repeated from its new perch on the messenger tern cages, and Bovril giggled. The two creatures began to whisper nonsense to each other, as they always did when they met.

Alek pulled his gaze from the eagle. 'In fact, I’m more interested in the message it was carrying.'

'Ah . . .' Her hands began to roll up the scroll. 'I’m afraid that is a military secret, for the moment.'

Alek scowled. His allies in Istanbul had never kept secrets from him.

If only he could have stayed there somehow. According to the newspapers, the rebels had control of the capital now, and the rest of the Ottoman Empire was falling under their sway. He would have been respected there-useful, instead of a waste of hydrogen. Indeed, helping the rebels overthrow the sultan had been the most useful thing he’d ever done. It had robbed the Germans of a Clanker ally and had proven that he, Prince Aleksandar of Hohenburg, could make a difference in this war.

Why had he listened to Dylan and come back to this abomination of an airship?

'Are you quite all right, Prince?' Dr. Barlow asked.

'I just wish I knew what you Darwinists were up to,' Alek said, a sudden quiver of anger in his voice. 'At least if you were taking me and my men to London in chains, it would make sense. What’s the point of lugging us halfway around the world?'

Dr. Barlow spoke soothingly. 'We all go where the war takes us, Prince Aleksandar. You haven’t had such bad luck on this ship, have you?'

Alek scowled but couldn’t argue. The Leviathan had saved him from spending the war hiding out in a freezing castle in the Alps, after all. And it had taken him to Istanbul, where he’d struck his first blow against the Germans.

He gathered himself. 'Perhaps not, Dr. Barlow. But I prefer to choose my own course.'

'That time may come sooner than you think.'

Alek raised an eyebrow, wondering what she meant.

'Come on, your princeliness,' Dylan said. The eagle was now hooded and perching quietly on his arm. 'It’s useless arguing with boffins. And we’ve got a bird to feed.'

© 2011 Scott Westerfeld