‘Fuck postcodes,’ said Beverley. ‘This is a no-fly zone, UN resolution-breaking, war-starting stuff. You know my mum and the Old Man of the River, remember all that aggravation? That’s nothing compared to what’ll happen if we don’t get off this ridge right now.’

‘I get that,’ I said. ‘But who?’

‘I don’t know, Peter,’ said Beverley. ‘And I don’t think it’s a good idea to stick around to find out.’

I heard hoof beats to the north-east, behind us. The fucker must have circled around or just stood invisible in the wings and watched us walk past.

‘Which way?’ I asked.

Beverley hesitated and then thrust out an arm in a vaguely south-westerly direction.

‘That way,’ she said. ‘Towards the river.’

Away from the unicorn – it seemed like a sensible idea.

‘I thought you were going to make friends,’ said Dominic as he headed off at a brisk pace.

I would have explained that operational flexibility is the key to successful policing, but I decided to save my breath. I also left the cricket bat and the werelight behind me in the hope that it might slow down whatever was following us.

‘How far is it to the car?’ I asked.

‘Don’t know,’ said Dominic. ‘Half a mile?’

I stopped and looked back.

A hundred metres behind me the unicorn had stopped beneath my werelight to bask in its glow. As I watched, it reared up on its hind legs, the reddening light gleaming along its horn, and gave a deep rumbling bellow.

Nothing that ate grass, I decided, would make a noise like that and legged it after the others.

Suddenly the forest on our left gave way to a single line of trees reinforced with a barbed-wire fence and, on the other side, open pasture silver in the moonlight. Beverley stopped so fast that I nearly ran into her back.

‘That way,’ she said, pointing at the pasture.

I was about to ask why we couldn’t just keep going when I saw something blocking the track ahead. In the darkness it was an indistinct pattern of shadow, but when it moved my brain had no trouble filling in its outline – another unicorn.

‘Oh, great,’ said Dominic.

I looked back to where the werelight was flickering and our prancing friend came whumping down on its front hooves, head lowered like a bull. I swung back to the fence looking for a stile or a gate, or even a gap that wouldn’t involve ripping myself to bits on the barbed wire.

‘Peter,’ said Beverley – I heard hoof beats from both directions.

‘I know,’ I said trying to clear my mind.

‘Hurry,’ she said.

‘I know,’ I said, summoning up the impello forma in my mind and trying to remember the formae inflectentes that would make it do what I want.

‘I mean it,’ she said, and I let the spell go.