But if I can still think, then perhaps I’m still here? she wondered stupidly, as those very thoughts blurred and slowed.

‘Winters!’ Vale had her by the shoulders and was shaking her, but she could hardly feel it. It was as though the sensations were being reported to her from a great distance. ‘Fight back, woman. You’ve fought worse. Remember – you still have free will!’

How amusing of him to think so. That wasn’t even Irene’s own reaction. That was Alberich’s thought seeping through her mind. She felt it split for a moment into a whole layered set of thoughts about Victorian Christianity, English hypocrisy . . . and the cold certainty that anything and everything could be broken if one had the right tools. Then it coalesced into a thin stream of mockery which ran through Irene’s thoughts like metal veins in rock.

Catherine tried to pry the pendant off Irene’s chest, protecting her hand with a fold of her dress. But the pendant clung to Irene’s skin as though melted in place. Irene heard herself manage to scream at last, but it was like hearing someone else’s voice.

And soon it will be, Alberich said inside her mind. It will be my voice and my body. With this body, I won’t need Lady Guantes and her doors, and the Library itself will be mine for the taking . . .

‘Alberich!’ Vale’s fingers tightened on her shoulders, and he looked squarely into her eyes. ‘You’re there. I know it. Release her, man, or you’ll have killed your own daughter!’

Inside Irene’s head there was a moment of sudden baffled shock but at the same time there was comprehension. A dozen faceted thoughts tumbled through Irene’s head, and she was no longer certain if they were Alberich’s or her own. Daughter of two Librarians . . . didn’t even know she was adopted . . . able to use my wards, able to break my wards . . . with her own blood . . . a good liar . . . cunning with the Language . . . looked me in the eyes, told me she was like me . . . should have known . . . could have guessed . . .

But she had no time to study the fragmentary ideas that fell through her mind like broken glass. Instead she formed them into a single connected thought with a surface as smooth and reflective as obsidian, and slid it between Alberich’s mind and her own. She took full advantage of his brief uncertainty and his belief in Vale’s lie. You. Me. Separate.

The pendant suddenly came free of her chest; Catherine dragged it over her head, hurling it to one side. Irene’s back arched as she screamed again, as the last vestiges of Alberich were stripped from her mind, leaving her – her soul, she supposed – feeling agonizingly raw.

The overhead lights dimmed to blood-red and thick shadows cloaked the shelves and columns, as the tide of chaos finally ebbed to a level more natural for this world.

Irene looked around, exhausted but taking stock. The inside of her head felt as if she’d had a particularly rotten molar extracted after a great deal of pain, but there was no time to rest. Vale and Catherine were nearby. Kai and Shan Yuan had both struggled to their feet, and now that the chaos levels were dropping, they were at least the equal of normal humans. Kai had Lady Guantes in an armlock, suitably restrained, with his other arm looped round her neck.

All the Fae’s plans had come to nothing and Lord Guantes’ stored personality would be lost, with their technology denied to them and no fresh host body to commandeer. Her expression was blank, as though some animating spirit had deserted her. Was this some side-effect of her broken oath, or simply the knowledge of defeat? ‘I suppose you want a way out of here,’ she said, her tone abstracted, flat, like a child repeating the rules of a game. ‘We can make a deal, I’m sure.’

‘Irene?’ Kai asked, his tone grave, and she knew what he was asking.

She didn’t want this, but she couldn’t see any other choice. Lady Guantes had defined herself by her husband – and by her need for revenge. Any truce would be temporary, or a lie, after what had happened here.

Irene jerked her head in a nod, and Kai snapped the Fae’s neck.

It was cold comfort to know that he’d taken Lady Guantes by surprise and it would have been over in a flash. This did nothing to ease the weight of what Irene had done. And it didn’t help that neither Vale, Catherine nor the dragons uttered a word of blame. They hadn’t made the decision. They’d left it to her.

Irene looked at Lady Guantes’ body as Kai laid her down on the floor, feeling the bitter knowledge that she’d murdered the Fae turning over and over inside her. Kai could shrug it off easily enough, as a royal dragon with a feudal upbringing. But Irene knew that she’d relive this scene in her dreams. This wasn’t why I became a Librarian . . .

The sound of running feet – multiple booted feet, coming in fast – broke the silence, and they all turned towards the noise. That was their only warning but it was enough, when the first bullet came singing out of the darkness, for Shan Yuan to push Kai out of the way. The bullet took him in the shoulder, knocking him to the floor. A barrage followed, and they all scrambled for cover.

‘Guns, jam!’ Irene screamed as she threw herself down and out of the direct firing line, and the bullets abruptly stopped. They were trapped in the middle of an open space, their only refuge being the experimental table and the painted door, and their aggressors stood between them and the nearest exit.

‘Hold fire!’ That was Lord Guantes’ voice. He was concealed somewhere among the shadowy shelves. ‘Your guns won’t work – use the gas.’

The Language couldn’t repel gas effectively. ‘Retreat!’ Irene called, scrambling to her feet and pulling Catherine with her.

Gas grenades were clattering into the area by the table as Irene and Catherine reached the shelves opposite Lord Guantes and his men. Kai and Vale were a few seconds behind, supporting Shan Yuan between them. ‘Which way?’ Kai demanded, most of his attention on his wounded brother.

‘Straight ahead until we hit a wall, then sideways till we find a door—’ Irene started.

‘That’s not necessary,’ Catherine said, sudden certainty in her voice. ‘I know the way out. Here.’ She pointed with authority.

‘We need to escape this world, not just the cathedral, and neither Shan Yuan nor I can take our true forms. If we can’t fly, how can we leave?’ Kai’s eyes flicked to Catherine, and Irene heard what he wasn’t saying. We could all break out via the Library; she can’t. We can’t just leave her.

Except – perhaps – was there a way she could get Catherine into the Library? ‘Run first, I’ll explain later,’ Irene directed.

‘Lord Guantes brought me down this way before and I remember it. Follow me.’ Catherine led the way at a run, flitting between bookshelves and pillars without a moment’s hesitation.

In the near-darkness the archive was harder to negotiate. Irene followed Catherine as closely as possible, unwilling to let the girl get out of her sight. Vale’s lie to Alberich flashed through her mind. But it couldn’t possibly be true, so she ignored it and focused on running. She could smell acrid gas on the air – not close enough to affect them, but close enough to remind her of the danger they faced. Lord Guantes could simply lock all the doors, turn off the ventilation and leave them to suffocate . . .

‘Over here . . . there’s a door!’ Catherine had just reached the edge of the vast room. She pointed to her left, at something Irene couldn’t yet see.