‘I see.’ Bradamant did a good job of drooping in response to Silver’s accusations. ‘Then you know everything.’

‘Everything!’ Silver declared. ‘I am not surprised that Aubrey should have called for reinforcements from the Library with such a prize at stake, but now he will have to admit that he has failed. Our long rivalry is at an end!’

Irene blinked in shock. No. No. That couldn’t be right. If Silver had known Dominic Aubrey, and had learnt that he was a Library agent, then Dominic should have known about Silver being a threat. But Dominic hadn’t said a single word about Silver being an enemy of his, or warned them about him, or even told them that Silver existed . . .

. . . and why was Bradamant nodding? What did she know? ‘Aubrey warned me about you,’ she said, ‘but I believe he did not prepare me enough.’

No, surely this was impossible. There was no conceivable reason for Dominic to warn Bradamant, but not her or Kai. They could well have come into contact, as the only door to the Library was in Aubrey’s office. But there had been no sign that they had exchanged this sort of intelligence. Of course Dominic might have had his own patrons in the Library, who wanted Bradamant to find the book first. That was entirely plausible, and wasn’t even an offence as such. But deliberately hiding the threat of Silver from her and Kai wasn’t just a casual slip, it was a betrayal. If she’d got back and told her superiors, then Dominic might well have been removed from his post.

Could Bradamant be lying? Her thoughts rattled in her head like computer keys. And the tension in the room escalated as Silver considered his next dramatic reply, as Vale and Kai shifted their positions behind her, and as the werewolves panted and waited to lunge.

No. It didn’t fit. Oh, all right, maybe Bradamant and Silver might be secret allies staging an argument to convince her. But that was taking paranoia too far. So if Dominic knew about Silver and considered him significant enough to warn Bradamant – but didn’t even bother mentioning him to Irene on the next day, when he knew Irene was on a confirmed mission – then what did that imply? What had changed?

She thought back to her brief contact with Dominic Aubrey. His use of the Language was strangely old-fashioned. And then there was Dominic Aubrey’s disappearance and skinning, which left his library tattoo intact but no sign of his body at all. And how did Alberich operate in this alternate world? Alberich, who had lived for long enough to be a legend even among the Librarians . . . but nobody knew how, and nobody even knew what he looked like.

An idea was forming, an idea that she mentally flinched from, but one that answered a lot of questions. Stealing someone’s skin and identity was covered in obscure folklore treatises, but it wasn’t something that she ever expected to be real. She didn’t want it to be real.

Silver had advanced on Vale and was flourishing his cane menacingly. ‘Wyndham only wanted the book because of information I gave him. Then he thought he could bargain for it. With me! Why, if the Iron Brotherhood hadn’t disposed of him, I might have been forced to do so myself . . . But all is not lost, my dear.’

So it was the Iron Brotherhood that had killed Wyndham. Assuming Silver was correct about it, that tied off one loose end. Good, Irene thought, at least that’s one less unidentified group of assassins running around the place.

Silver took a step forward, smiling brilliantly. Irene felt the air tingle with suppressed longing again. ‘Hand over the book and I will be glad to agree to any terms that you might desire.’

Over by the desk, Ramsbottom seemed poised to tell all. His hand wavered towards the small blue ledger.

Kai was the one who moved. He sprang forward like a leopard, and threw himself into a running dive across the desk, snatching the incriminating ledger out of Ramsbottom’s hands. He tossed the ledger across the room to Irene and it spun through the air in a flutter of pages.

‘Get that!’ Silver shrieked.

Irene caught it.

‘Back, ladies,’ Vale snapped, as a swift twist of his hand revealed the sword inside his walking cane. The length of steel glittered in the burning glow of the lamps, and with a sudden crack sparks cascaded down it, flaring up harshly between them. ‘Lord Silver, restrain your dogs!’

Kai was pushing Ramsbottom back against the wall, getting between him and Silver’s snarling minions. Good for Kai, keeping the civilians out of it. Silver’s minions were getting hairier by the second. Irene could see the spreading patches of iron-grey and black matted fur on their hands, their lengthening nails, their bulging jaws with sprouting teeth . . .

‘Come on!’ Bradamant grabbed Irene’s shoulder, pulling her towards the door.

Pure animal terror at the thought of being torn apart by half a dozen large wolves voted in favour of escape. Explanations could wait.

She stumbled out into the corridor behind Bradamant. If they ran to the right, they’d be leading the chase back towards regular museum visitors. And that would not only be morally invidious, but would probably put them off museums for life.

Irene tucked the ledger under one arm, picked up her skirts, and sprinted leftwards. She heard a muffled curse as Bradamant followed.

Two junctions later, she paused at a spot where two corridors crossed. The place was a rabbit-warren. The air to the right smelled fresher, which argued a way out to the ground floor, or at least a fire escape of some sort, but the passage to the left was better lit. The passage directly in front had nothing to recommend it.

‘Keep going,’ Bradamant ordered, pausing to catch her breath. ‘The werewolves are right behind us – ’