You died in your forties. You’ve got ten years on me, if that, Walden thought. But she took her grandmother’s owl brooch out of her skirt pocket. She jammed it pin-first into the wall, with some force, and looped a spell around it to make sure it stayed firm. When she let it go, the enamelled owl was shining with pale golden light: a beacon, to mark the way back.

Walden followed the ghost.

This was definitely not the present-day School House. The staircases groaned and sagged underfoot in a way that spoke to terrible rottings and splinterings in the dark below the floorboards. Todd Cartwright would have been appalled. And although it was hard to see detail through the greasy fog of the demonic plane, the rooms here seemed much smaller and darker than the light and airy house that Ebele ran now. Walden at one point caught a glimpse of a wall-fitted gas sconce. Occasional figures moved through the fog; imps latched onto echoes of emotion, perhaps, like the schoolmaster she’d dismissed. Boys, mostly. Chetwood had been a single-sex establishment until 1963.

The sobbing was hardest to bear. It rose and fell, and the timbre varied, though it tended towards the treble. Boarding schools nowadays prided themselves on being homes away from home for your darling offspring, all life and fun and well-resourced pastoral support teams. In the nineteenth century, ‘pastoral’ meant poems about sheep. Walden followed Merringham’s ghostly figure through spartan dormitories with glitters of frost on the insides of clouded windowpanes. The stifled whimpers of unhappy children echoed in her ears. She reflected in passing on how much history had been made by men presumably suffering from the aftereffects of traumatic childhood neglect.

A welcome stretch of relief came when Merringham’s ghost led her across a silent space which seemed to be the long-lost kitchen garden from School House’s pre-Victorian incarnation. A bit peculiar, since by that point they’d climbed several flights of stairs, but Walden caught a trace of lavender scent and saw a knee-level motion in the fog which might have been the suggestion of a chicken. I ought to be taking notes, she thought. Critical incursions were poorly understood, mainly because they were very dangerous and everyone tried to make sure they never happened. Attempts to simulate a crisis like this took place in areas where no one lived, or wanted to live. But School House’s long history was casting its shadow over the demonic plane here.

Eventually, a doorway became visible through the fog from a distance. Painted on it in lines of white light was the intricate shape of an incursion ward. Not an old one either. Walden knew what modern spellwork looked like. She only became more certain as Merringham led her closer. She’d marked enough of Nikki’s homework to recognise her handwriting.