There was a definite hole in the heavy material of Guleed’s Public Order boiler suit that widened when I stuck a finger in it to reveal a matching slice in the white t-shirt underneath.

‘Ow,’ said Guleed. ‘Careful.’

It would have taken way too long to dig out my pocket knife, so I chopped the cloth with a spell Nightingale had taught me – he’d made me practice on letters and Amazon packaging. I pulled up the T-shirt to reveal a long scrape along her waist. I prodded it, which made her wince – but the skin seemed unbroken.

‘It’s a scrape,’ I said. ‘You’re going to have a lovely bruise.’

There was a thump on the fire door, followed by gunshots.

I looked at Guleed, and she looked at me, and we both stood there dithering and thinking that about now it would be nice to have a little bit of command and control, when down the stairs thumped DI Stephanopoulos with Bill Conti’s ‘Fanfare for Rocky’ playing in the background, and what looked like half a carrier of TSG piling up behind her.

‘Just a scrape, boss,’ said Guleed before Stephanopoulos could say anything.

Stephanopoulos looked at the door.

‘The Americans?’ she asked.

I filled her in.

‘But we don’t even want to be on this floor,’ I said. ‘We’re supposed to be checking the garage.’

‘In that case we’ll secure the stairs while you go down,’ she said. ‘If the Americans try to come in, we scoop them up – otherwise we wait until we get some more bodies in here.’

She stabbed a finger at Guleed.

‘You,’ she said, ‘be more careful. And you,’ she turned to glare at me, ‘just try to be a little less Peter Grant on this outing.’

I had a witty comeback all ready to go, but at that point the whole staircase shook. There was a shower of fine grey dust all around us as the joists securing the staircase to its frame ground into the concrete.

Stephanopoulos’ Airwave squawked and Seawoll reported that Martin Chorley’s flat had just lit up like a fireworks display. I could feel it, too, amongst the bangs and shrieks that echoed down the stairwell. Forma and counter-forma, a full-on magical duel. Nightingale was going head to head with someone formidable – Martin Chorley, at last?

I opened my mouth, but Stephanopoulos put her hand up for silence.

‘Wait,’ she said.

‘But—’

Three gunshots from beyond the fire door, but not that close. Two more further away. Then running feet right outside, five or six shots, loud, rapid, desperate. I tensed, but Stephanopoulos shut me down with another glare.

‘Wait.’