Kai didn’t seem to realize quite how much danger he’d been in. He’d just shrugged it away: he’d been poisoned, received medical care, recovered. Catherine at least seemed to have a more sensible appreciation of the situation. Irene wished she knew more about her student’s history. She kept on thinking of her as the girl, as she seemed so young. She claimed to be in her thirties – but really, how could a human tell a Fae’s real age? Either way, she remained an unknown quantity at an uncertain time.

Sterrington’s office was in one of the new buildings. It reared up ominously among the surrounding establishments, a structure in dark iron with windows as black as obsidian. Two small zeppelins floated above, tethered to the roof in permanent readiness to rush off on urgent business – a display of ostentatious wealth declaring We have money to waste. A constant stream of visitors flowed through the rotating doors, and Irene was glad to lose herself among them. Inside, her progress was further slowed by a group of workmen repainting the lobby. It was oddly reassuring to find this dark monolith of business wasn’t as perfect as it looked.

To Irene’s surprise she was shown to Sterrington’s office immediately. She was whisked past two secretaries and a roomful of clerks, and Sterrington actually rose from her desk to greet her. ‘Thank you so much for coming at once,’ she said. ‘I do appreciate it.’

Irene shook Sterrington’s mechanical hand, feeling the workings of metal and plastic under the woman’s silk glove, and wondered what she’d missed. ‘I’m glad if this is timely,’ she said, ‘but I have to admit I came about my own problems. If you sent a message to my lodgings, I haven’t been there since yesterday.’

‘The important thing is that we can have a face-to-face, high priority.’ Sterrington gestured Irene to a chair opposite. Her dark hair was restrained in a tight bun, and her face had the sort of smooth gloss that went with a perfect cleansing regimen. Her watered silk grey jacket and skirt radiated ‘high-status businesswoman’, topped off with a single ruffle of white silk at her throat. She came straight to the point. ‘Yesterday I received an urgent message from Lord Silver. One of his spies warned him someone was plotting to assassinate him. So he was planning to leave London, without alerting any watchers that he knew of the plot. He thought I was involved too.’

‘As additional target or as an assassin?’ Irene asked innocently.

‘Target,’ Sterrington said. The Fae didn’t seem insulted, which said something about her professional relationship with Lord Silver. ‘His contacts told him you were at risk as well, and he asked me to tell you for the sake of the treaty. I expect he left a message for you too.’

‘More than likely,’ Irene agreed. ‘I need to check my lodgings; the problem is doing it safely . . . we experienced an assassination attempt ourselves, in Guernsey. It was almost a success.’

‘“We” being?’

‘Myself, Prince Kai, Peregrine Vale and Catherine. It’s the identity of the assassin that’s relevant here. You see . . . Lord Guantes came back from the dead.’

‘I find it alarming that you believe this.’

‘So you think I’ve been fooled?’ Irene asked.

‘Let’s say I think you should reconsider,’ Sterrington said. ‘Firstly, necromancy may be practised in some worlds, but it doesn’t work on my kind. Secondly, you definitely killed Lord Guantes. I should know. I spent over an hour sitting in the same train carriage as his dead body. Thirdly, I believe you think you’re speaking the truth. Therefore – lastly – you’ve been deceived in some way. Perfectly understandable, of course. But you haven’t told anyone else . . . have you?’

Irene clicked her tongue. ‘Really, Sterrington, give me credit for not being entirely lacking in sense.’

Sterrington flushed. ‘I should have known better,’ she said, neatly avoiding an actual apology. Fae didn’t like admitting error any more than humans. ‘It’s just the Cardinal wouldn’t like such rumours. It upsets the political balance. I don’t suppose you have any evidence to back up your wild claim?’

‘I do, actually, but it’s with Kai for analysis.’ Trusting anyone was a gamble, and Sterrington had worked for Lord Guantes before. But Sterrington’s current patron, the Cardinal, was in favour of the peace treaty. As such, they might even count on his and Sterrington’s aid. She ran through the details and saw doubt drift across Sterrington’s face like a shadow crossing the moon. ‘So you see,’ she finished, ‘I have valid evidence—’

‘Of something, certainly,’ Sterrington cut in. ‘I wish you’d given me that laptop. We have our own expert analysts, you know.’

‘Did the world I described sound familiar to you?’ Irene asked, dodging the subject.

Sterrington looked thoughtful, turning her pen over and over between gloved fingers. ‘Not specifically. It sounds like a world with a high degree of technology, and chaos, but there are so many of those. However, I find your description of that door into it rather worrying.’

‘Why worrying?’

‘Because of what it implies.’

‘Sterrington, I’ve seen Fae travel between worlds on their own, or through the agency of a more powerful Fae. That wasn’t treated as in any way unusual. And dragons can move between realms too . . . Is a permanent door between two worlds something new?’

Sterrington took several seconds to answer. Finally she said, ‘It’s new in my experience, and yes, troubling. There are legends that it is possible, but . . . different spheres,’ she used the Fae term for alternate worlds, ‘aren’t meant to be tied so closely together. It’s very bad for both realms.’

‘That’s not encouraging.’

‘No, it isn’t. I may need to report this.’ Sterrington pulled herself together. ‘I still don’t think you saw Lord Guantes, though. Whoever threatened you is an impostor, or a clone, or a brainwashed minion . . . or something else set up to confuse you. You want to be looking for the person you didn’t see.’

‘And who is that?’

‘Lady Guantes,’ Sterrington said. ‘She’s trying to taunt you, using her dead husband. It makes perfect sense that she’s behind the recent attacks upon you and your friends. And she’s trying to kill me because I failed them, then took a new patron.’

‘But how could they predict that I’d even be there with Vale, never mind that I’d find – and open – that door? Then see Lord Guantes waiting there . . .’

‘May I be frank?’ Sterrington asked.

Irene sighed. This was always the sign of a fast-approaching insult. ‘Do go on,’ she said drily.

‘With the utmost respect, anyone who knows you would expect you to investigate a potentially dangerous door while already facing a life-or-death situation.’

Irene liked to think of herself as sensible, but she couldn’t deny she’d gone through the door. ‘I viewed it as a rational step in an urgent investigation,’ she said with dignity.

There was a nagging feeling at the back of Irene’s mind, however. It suggested that any hypothesis which fitted the data so conveniently was by nature unreliable. ‘But why?’ she said. ‘What good does it do Lady Guantes to kill us? And why now, after all this time?’