It was a big one, a triple array straight out of Nielle’s Arrays, and very competently done; Walden would have graded an undergraduate highly on a piece of work like this, provided they hadn’t then used it to try to summon something about five times bigger than it was designed to hold. The first and second circles had broken down completely. There was so little left of the outermost pentagram that Walden had already stepped over it before she realised it was there. The second circle still had some traces of power remaining, but most of it was sputtering sadly, useless and undirected.

Nikki and Mathias were trapped in the innermost circle.

The third pentagram, at their feet, had transformed from a drawing in salt and chalk to a sucking black void. Walden saw Nikki step towards it, two little shuffling steps, and then back away with one big step; then forwards, two more little shuffles, and back: dragging herself away. If she stepped into that darkness, she would be possessed at once. The demon was pulling her in. Mathias, on the other side of that black maw, was on his hands and knees, shuddering.

Small mercies, Walden thought. It started with the tougher nut to crack.

There was no time to plan or to hesitate. Walden went briskly forward under her shield. She put a teacherly hand on Nikki’s shoulder and shoved her sideways. Nikki stumbled and fell, shrieking in terror as Old Faithful’s tug dragged her forwards at the same time.

“I think not,” said Walden, and stepped into the black hole that was the central pentagram.

There was a howl of irritation somewhere in the violet fog of the demonic plane, and the void roiled under her feet. Walden felt Old Faithful trying to tug her down. She held her right hand high and her left hand spread out—the oldest, simplest gesture of sorcerous command—and spoke in syllable after precise, focused syllable. The spells rolled confidently off her tongue, defining, compelling, demanding. A thousand years of the European magical tradition, six centuries of Chetwood School, and more than twenty years of study and practice had created Dr Walden. Old Faithful was a lot bigger than she was, but it had never had to work.

Her hands were trembling and her blouse and vest were stuck to her back with sweat by the end. The void still licked at her shoes. “BEGONE,” she finished. “Or else.”

The black maw closed over. The central pentagram ceased to be a howling hole into endless darkness and became Nikki’s scuffed bedroom floor.