The worst part of it for Endellion was that the archaeologist's plan almost succeeded. In the chaos of the blaze, he had found a free ornithopter, struggling into the seat, cranking the stiff mechanical wings into life. He'd have been safe in Gilliad within days. But they had both reckoned without the determination of that callous, loathsome General who, drunk as he was, ignored the death of the girl and the screams of his men.

He ignored the heat of the fire spreading through the airharbour, dashing after the traitor. Just as he was about the take-off, the General flung himself at the archaeologist. The wings cracked and then it was over. The archaeologist was a scholar not a soldier. He didn't stand a chance.

The archaeologist was knocked out when the General brought him to Endellion, shouting about thieves, treason and stolen artefacts. She tried not to shake as she examined the man's battered body. His hands were charred.

'His pockets?' she said to the General.

'Nothing of interest,' he replied.

The Librarian tried not to look too relieved. 'And the box?' she said.

The General shook his head. 'It will be safer in the barracks. Things are too easily stolen from unlocked offices.' His voice sounded reasonable, but his eyes were cold.

He knew.

The Librarian nodded.

She put on a false laugh. 'You know scholars, General. Forever forgetting to lock things.'

The General said nothing. She would need to be more careful from now on.

She watched him leave the room, carrying the archaeologist to the infirmary in his massive, muscled arms. Why in the Sky had she ever made that brute Guardian?

And now to the damage, she said thought, sighing. Getting the box back would be difficult enough as it was, and nigh on impossible now she had to deal with the disaster at the air-harbour.

Two of the General's men died in the end. One at the scene, and one, later, of his burns. What they had been doing in the ladies dorms of the college, Endellion didn't want to know. But they weren't the problem. They were mercenaries. Disposable.

But the loss of Viola Swift, the surgeon's only student, was worrying. Very worrying. How could the city survive with only one healer left? What would happen when dear old Magog died?

And then there was the archaeologist's trial. The Librarian fought the tears. She wouldn't let them kill him. No, she forbade it.

The Wyvern had survived, thankfully. It did not fear fire, it was not a creature that burned.

In fact it was the creature's shrieking that had woken the city from its half-drunk slumber. Had given them all precious minutes to find the hoses, flood the blaze with water, to save the lower tier of the city.

Endellion could hear the wyvern screeching again. The curator at the Museum of Natural History was determined they should keep the creature. Workmen were moving the mammoth skeletons out of the way as they spoke, he told Endellion in the twice hourly updates of excitement he sent her. It was ironic, Endellion thought, that the creature whose flames they had feared had saved the city from fire for good. Endellion tried to stop herself getting too annoyed at the curator: he was a true scholar, she realized, something the city sorely lacked these days.

And finally there was Menmar's own niece, found passed out in the cemetery of St Giles. Endellion knew she should rightly be stripped of her wings for such behaviour, be denied the right to take the Fledging. Indeed, she sometimes wanted to do it to spite the General himself, who doted on her. But Arrow was her grand-daughter too.

Now as Endellion stared at the red-eyed girl slumped in the chair in front of her, arms folded in stubbornness, Endellion knew she could not do it. As she dismissed the girl, she thought how much she reminded her of herself at that age, and looked at the picture of herself beside her airship.

Arrow would make a worthy captain, Endellion realized. She takes after me.

But then it hit her. Jude the Obscure. It had burnt in the blaze, the ship aflame. Endellion the Voyager, who had once dared fly into the maelstrom that cycled perpetually in the old Atlantic was now truly Endellion the Librarian.

The Librarian looked out from the window of her office in the dome of the Library. The ash had been scrubbed from the lower tier, and the wrecked airships removed. But the buildings were still boarded up, and there was barely any wood or fuel left. This would be a long winter.

She gazed out at the sea of cloud, undulating white, the sun beating down. At first she thought it was a stain on the window. But no it was flying. Flapping. Dark wings stretched out like a sign. Another wyvern! she thought, her inner scholar excited again. If she wasn't so busy, she could get back to her studies on animal migration! Find out why the animals were so far west.

But, no, it wasn't a wyvern. Just a trick of perspective. This bird was smaller. A brown, feathered thing, flying towards her like something out of a dream. She stared at it with awe. A woodpigeon, this high above the cloudscape? But something stirred in her memory. A wrinkled green face, framed by a brown beard. It was the only reason a woodpigeon would be at this altitude. She flung open the window, and the bird flew in, collapsing on the desk.

She picked it up gingerly, murmuring soothing words. She prised the letter out of its talons, her eyes scanning the page. There was sweat on her palms and her breathing was fast. How did he know so much?

But she didn't care. In her moment of need, Aeolus had answered her. She glanced again at the photo of her beside Jude the Obscure. Those years weren't over yet, she realized, and they never would be – Oxford would always be flying, always be running, to protect books from those who wanted to burn them. She knew immediately what she had to do. She picked up the speaker phone, dialled the Wheelhouse of All Souls, where scholars who had passed the exam spent their seven years steering the city, and spoke down the mouthpiece. Her tone was brisk, brooking no argument.

'Set a course for the Forest, we are going home.'

And so as September opened into October, the sky-city crossed the Volga, but didn't drop anchor. There was muttering as she entered the skies over Praag, bearing west, over Gilliad, and over the green expanse of the Forest. This time, the city really was going home. Of course, Endellion put out that they were stocking up on wood and other supplies, and that the scholars had sensed a colder winter, so the usual roost just west of the Volga was too harsh. But, nonetheless, the city was further west than she'd been for half a century at least.

In years to come, Endellion would sit at her desk in the Library, and reflect that this story began with the three of them, the hobgoblin, the wolf-girl and the sky-sailor. With plotting and lies and treachery, as the sky-city fled the untold years spent sailing through the clouds, with the savage vestige of humanity on their knees before these Birdmen, these Angels, these Silverbloods. For the prodigal city, she would lecture to her classes of the future, the story told of how they dug up the past and buried their future. Endellion would tell them she had known at that moment that her story was now over, her part was done, only to flit in and out from thereon. Like all tales of blood ever told, she would intone, we begin and end with a healer trying to repair it all…