Irene folded the letter. ‘His signature follows, then the appendix – though I don’t know any of the names in it.’

‘I’ll check the Fae names,’ Catherine said, taking the letter. ‘I might recognize someone.’

‘That’s all. Unless there’s spycraft involved – an encryption code, a cipher in the watermark, or something . . .’

Shan Yuan turned to his brother. ‘Kai, your thoughts?’

‘It is a positive that the Cardinal is on our side,’ Kai began, then saw his brother’s growing frown and added hastily, ‘As much as any Fae ever is. And all clues seem to point towards artificial intelligence in some way. However, if the Cardinal is sending more agents here, this London could become increasingly . . . dangerous.’

The euphemism hung in the air. If the Cardinal considered Lady Guantes to be a serious threat, he’d want to kill her and tear up her organization root and branch. And God help poor London, caught in the middle.

‘We really need a lead,’ Irene said firmly. ‘Inspector Singh, does the arson insurance fraud offer anything useful?’

‘No,’ Singh said with a sigh. ‘I’m afraid not – in the short term, at least. My opinion on the situation, ma’am, is that you should let your enemies come to you. We know the city – so you’ll have the advantage. And London’s police will be on hand to shut them down.’

‘I disagree.’ Vale had a new look in his eyes; the hound on the scent, the hawk who’d spied a rabbit in the long grass. ‘We have no idea what our adversaries might bring in from other worlds, through these doors that Winters has described. And we do have a lead, based on something most of the attacks have in common.’

Singh frowned. ‘Yes, I remember you saying. So what exactly did you find in the Foreign Office reports? The ones your sister provided?’

‘They covered the cerebral control devices, which were present in several incidents. It seems possible that their inventor, Doctor Brabasmus, isn’t even dead. When the local police checked his laboratory, after the explosions that destroyed it, they found a decapitated body. The evidence suggested multiple physical invasions via the cervical spinal canal, and exit wounds via various orifices. The head was thoroughly destroyed. Under the circumstances, at the time, everyone made the logical assumption that the doctor had perished.’

‘You said . . . decapitated,’ Irene murmured, trying to keep her visualizations to black and white rather than enthusiastic images in pink and red.

Vale shrugged. ‘The skull was indeed thoroughly detached, and no firm identification could be made via the teeth. Dentures, alas. But given certain indications in the reports . . . I believe he is alive. What’s more, I can guess at his location this very evening.’

‘The report from Paris?’ Singh frowned. ‘I read that one. It wasn’t what I’d call reliable. The writer said herself that the information was speculative and from a dubious source.’

‘We can’t be certain – but we must investigate.’ Vale leaned forward, intent on his trail of thought, ignoring the rest of the room. ‘Tonight Brabasmus has the perfect opportunity to attend an event – unrecognized and unnoticed – and meet a contact from the French government. Apparently, the contact wants the cerebral controllers, Brabasmus wants to sell them, and they will be meeting tonight at the People’s Palace. This is a chance, Winters. If we can take Brabasmus, we can question him about the Guantes. They’ve made good use of his controllers – so why not his research on harnessing technology to alter the mind? And that avenue leads us to Alberich. Who knows . . . maybe the doctor has even visited his headquarters.’

The sudden burst of possible hope that seized Irene was almost painful. ‘What is the People’s Palace, though, and why is it such good cover?’

‘The “Grand Technological Exhibition” is taking place there tonight,’ Singh explained. ‘It’s that place out by Wood Green – the one they might rename after the Princess of Wales.’

‘Will technological advances actually be on display?’ Shan Yuan demanded.

‘That’s the problem, sir. We don’t know what will be there. It changes every year. You see, your highness, the Grand Technological Exhibition is an annual celebration for, shall we say, over-enthusiastic men and women of science. The police always attend as it could end with a bonfire, explosions or even a riot. I’ve seen giant robots bounce through the streets – and once half the drains in London ran pink and grew fluorite crystals. One year, a new underground bullet train destined for Paris went to Edinburgh instead. But a particular favourite of mine, if you can call it that, was the personal glider-suit driven by underarm flamethrowers. You might also see devices for communicating with dolphins, and usually at least half a dozen machines that are supposed to end world hunger and enforce world peace. Those are usually the worst.’

‘Come now, Singh,’ Vale said, ‘your distress seems fresh, but they haven’t held the event in London for five years now.’

‘Maybe so. But after that last occasion, such a thing shouldn’t be allowed anywhere south of the North Pole.’

‘Inspector Singh, do you also think Doctor Brabasmus might be there?’ Irene asked, trying to steer the conversation back.

‘I’m not sure, ma’am,’ Singh said slowly. ‘Certainly it’s where all London’s leading scientists will be tonight. So it’s possible. It’s also possible that – based on the past record of some in this room, and naming no names – it’s the very last place we should go. We could end up with London in flames, flooded and under attack, with an earthquake splitting the city from top to bottom.’

It was awkward when people started making judgements based on one’s past record. Especially when they had a point. ‘Are you sure this is worth our time, Vale?’ Irene asked.

‘Winters, I would hardly have mentioned it if I didn’t think it was worth trying,’ Vale said impatiently, practically vibrating with a febrile keenness. ‘These cerebral controllers link several of the attacks upon us. We have few leads to follow, so I think we must pursue any and all that present themselves.’ He gave a nod to Shan Yuan, who returned it. ‘The French report tells us that the rendezvous between Doctor Brabasmus and his contact is scheduled for eleven o’clock, somewhere in the building. With the three of us to quarter the place in advance and find them –’ his gesture took in Irene and Kai – ‘we could apprehend Brabasmus and find out what he knows! And who is his contact, the person he’s meeting there? This could also be of interest.’

‘I dislike this option,’ Singh muttered. ‘We’ve known each other for years, and I’m telling you that I’m not convinced. I’m unwilling to hazard your lives, based on this one report. It could be a trap. It’s certainly not safe.’

Irene looked at Kai, and he gave her a slight nod. It said that he’d abide by her choice, whatever it was. While Singh might not want to risk them . . . it wasn’t his choice, or his responsibility, and they needed information.

‘Can you arrange disguises and tickets for us?’ she asked Singh. It was time to get practical, and stop procrastinating.