‘Perhaps. Cults and heretics do sometimes open them deliberately. But it could be a natural occurrence. Most are. The fabric of space is thin in places, you see, and sometimes there are leaks.’

He shook his head and a sad smile appeared under his heavy moustache. ‘I don’t actually know much about the warp, sir,’ he said.

‘Nor should you, commissioner. It’s forbidden lore. I’m just telling you what you need to know. There is a regia occulta in Jared County Town, and it’s right here.’

We were standing at the Commercia end of the New Bridge.

It took Zelwyn just a few minutes to have the bridge and its feeder roads closed off and barricaded by the militia. Another hour, and it would have been teeming with traffic heading in for work.

‘Can you tell me why this only happens when the bridge is up?’ Zelwyn asked. ‘I mean, surely that would block a crossing?’

‘I’ll do better than tell you,’ I said. ‘I’ll show you.’

We took up a position at the Commercia end; me, Zelwyn and four men from the militia armed with powerful autorifles. At my nod, the commissioner signalled to the bridge machine room on the far bank, and the operators engaged the hydraulics. Ponderously, with a dull squeal like gates opening, the massive spans began to lift.

The Cackle fluoresced in the dawn sky over our heads. Blue ropes of fizzling corposant writhed and trickled like snakes around the iron finials of the bridge towers, and traced their way along the rising edges of the gigantic metal spans.

The hydraulics cut out when the spans were at a standard lifted position, at about forty degrees from the horizontal. We waited, looking up the steep metal slope of the span facing us. Below us, out of sight, the fast-running river gurgled and hissed.

We waited for ten minutes. Corposant gathered in increasingly heavy ribbons around the raised tips of the bridge span, as if attracted there in concentration, like lightning drawn to a conductor.

There was a dry electric crack, and we smelled ozone. One of the militiamen pointed. A whip of corposant had flicked out from the tip of one span and connected with the tip of the other, like a squiggle of electrostatic voltage crackling between two insulated orbs. It remained there, jerking and sizzling, like a bright, twisting rope tying the two halves of the raised bridge together. This feature had not been evident in the patchy disposition Lana Howey had shown me, but I suddenly felt I had discerned the key mechanism of the infernal regia occulta.

One of the militiamen started to say something, but I already knew ‘it’ was happening. The hairs on my neck were raised. I felt something akin to a ball of ice in my stomach, and a searing pain behind my eyes.