‘This is Elvish script,’ I said.

‘I doubt that,’ said Nightingale.

‘Not real elves,’ I said, wondering if there were such a thing. ‘Elves as in Lord of the Rings elves, Tolkien. He developed his own language and alphabet for his books.’

‘This is all very interesting, boys,’ said Lesley. ‘And much as I like hanging around lethal devices, I haven’t had my dinner yet – so can we get on with the IED.’

‘IDD,’ I said. ‘Improvised Demonic Device.’

‘It doesn’t look improvised, anyway,’ said Lesley. ‘It looks custom-built.’

‘When you two are quite finished,’ said Nightingale.

Lesley looked outraged but kept her mouth shut.

Nightingale pointed at the empty boss. ‘This one was primed to go off at the first use of formal magic inside the flat,’ he said. ‘I think it was deliberately left behind to kill either of you two. Fortunately it was me that triggered it and I had time to contain and dissipate the effect.’

‘Or what would have happened?’ I asked.

‘It would have killed me certainly,’ said Nightingale. ‘And anyone in the flat with me. And probably would have shortened the life of anyone within twenty yards of here.’

I opened my mouth to ask what the deaths would have looked like, but Lesley silenced me with a glare – it’s impressive how much expression she can project out of those eye holes.

‘Luckily this is a nice modern building made of concrete,’ said Nightingale. ‘Not much in the way of vestigium in situ and concrete’s very absorbent. I’m going to channel the demon into the structure around us, much more slowly than I did with the first one. The spell I do will be far too fast for you to follow but I want you two to concentrate on the nature of the demon – that might give us a lead as to where it came from.’

Nightingale took a deep breath and in a weirdly ecclesiastical gesture brought two fingers down towards the second boss – he paused with his fingertips hovering above the metal.

‘This may be somewhat unpleasant,’ he said and pressed his fingers down.

Fucking major fucking understatement.

We didn’t throw up, pass out or burst into tears, but it was a close thing.

‘Well?’ asked Nightingale, who was obviously made of sterner stuff.

‘A dog, sir,’ said Lesley hoarsely. ‘Pitbull, Rottweiler, some ugly bastard thing like that.’

The second boss had crumbled into sand and one part of my brain was wondering whether that was the same phenomena that kept destroying my phones. And the other part of my brain was screaming that I was never going to eat meat again.

There had been blood and pain and mad exultation and concrete walls and rotting straw and then it started to drain away, exactly the way a nightmare does on waking. Leaving the memory of terror unwinding in your stomach.

‘Dog fight,’ I said.