‘What are the identifying marks for the book?’ She saw Bradamant begin to say something, and held up a hand to stop her. ‘Look. You said that you’ve already been fooled once with a fake. If it was your superior who sent you back – if you’re actually here with permission . . .’ She saw Bradamant’s eyes narrow in anger at that. ‘Then he wouldn’t have sent you back again without giving you some sort of way to identify the genuine article. Are you really going to risk losing the book because you’re not prepared to share that with me? A book which may be that important to this world?’

Bradamant’s glare was pure poison. ‘Don’t rush me,’ she said. ‘I’m thinking.’

‘Think fast,’ Irene said. ‘Vale will be coming to find us in a moment.’

‘Tale eighty-seven,’ Bradamant said. ‘The Story of the Stone from the Tower of Babel. If it’s there, then it’s genuine.’

‘Thank you,’ Irene said. She picked up her hat and veil, and skewered them in place with a hatpin.

Bradamant seemed about to say something but, with a visible struggle, managed to contain herself. She adjusted her own hat, then swept out, calling sweetly, ‘We’re coming!’

A few seconds later they were jumbled together into a hansom cab and heading to the Natural History Museum. From what Irene could remember of London’s geography, it was at least half an hour away – more, if the traffic was bad. Singh had muttered the instructions to the driver rather than shouting them loud enough to be heard across the street, and was now brooding in the corner of the cab. Kai, Vale and Singh were all sandwiched onto one seat, while Irene and Bradamant shared the seat opposite and tried not to look too comfortable.

‘Do you know who we need to speak to when we get there, Inspector?’ Vale asked Singh.

Singh nodded. ‘I have the name from last time – Professor Betony, and even if you can’t find her, then you can find her office in the Department of Cryptidology downstairs. With any luck, you can be in and out of there before anyone who might be following you catches up. We can then establish if the book’s here or not. And I’ll be getting that search warrant in the meantime.’ He gave Bradamant one of his flat looks. ‘And then this young lady can return the other books that she made off with.’

Bradamant flushed, lowered her eyes, played with the strap of her handbag. She looked in every way like an innocent young woman who had been led into crime by bad company and wanted nothing more than to make amends. Irene had to admire the performance, especially given Bradamant’s probable feelings of rage towards her.

‘Do you often get sent on missions like this for this Library of yours, Miss Winter?’ Vale asked Irene. He tried to make it sound like casual conversation, but she could feel the deeper curiosity beneath his words.

‘This one is a bit more . . . ah, dramatic, than most of them,’ Irene said, a little relieved that Vale was asking her rather than Bradamant. And that was perfectly true. She’d had dozens of missions where she’d simply wandered in, quietly bought a copy of the book in question, and left without anyone so much as noticing her. And at least ten assignments where there had been some minor illegality involved, but none had featured chases through the streets, dangerously flamboyant personalities or cyborg alligators. ‘There was a time before this when I was in France.’ Well, a France. There were a lot of Frances. ‘I was trying to secure a copy of a book about alchemy by someone called Michael Maier, a few hundred years old. It was called . . .’ She frowned. ‘Something about nine triads, and it contained intellectual songs about the resurrection of the phoenix, or something along those lines. I ended up getting involved with a group of Templars and having to leave in something of a hurry.’ About five minutes before they’d broken the door down, to be precise, but no need to tell Vale that bit.

‘And then there was the cat burglar affair,’ Bradamant said sweetly.

Irene felt her hands tighten in her gloves. She forced herself to stay calm. ‘Yes,’ she agreed. ‘There was that.’

Kai leaned forward. ‘What was this cat burglar affair?’ he asked.

Bradamant smiled in a sympathetic, understanding, non-judgemental sort of way. ‘Oh, it was when I was mentoring Irene, when she was first working in the field. We were trying to locate a book which had been stolen by a notorious thief. Everyone knew who she was. The best police officers in the city were watching her every move and still they couldn’t catch her. And when Irene and I were trying to investigate her, well . . .’ She smiled again, tolerantly. ‘The lady in question was very charming. And it isn’t as if I was in any significant danger while Irene was so, shall we say, “preoccupied” with her. And I managed to find the book, so all’s well that ends well.’

Irene looked down at her knees and bit her tongue. It hadn’t been like that at all, it hadn’t, but that was all the story that anyone would know now. Bradamant had cheerfully spread it all over the Library in murmured detail, and anything that Irene had said then, or could say now, would simply make her sound as if she was making excuses. The alternate had been one with a very specific set of social standards. Theft was a comparatively petty transgression there, even if it was illegal; immoral behaviour was the sort of thing which could entirely destroy a woman’s reputation. Bradamant had set the whole thing up, arranging an identity for Irene as a freelance thief herself, suggesting that perhaps the woman could be persuaded to hand the book over, and even fixing up an assignation. And then she’d simply burgled the woman’s house while Irene had been sincerely trying to talk her round. And Irene had been left floundering and making excuses, and trying to explain what had happened to the other woman’s house, and her possessions, and her reputation . . .