Old Faithful had agreed to fight. It hadn’t agreed to fight fair. This was no different than what it had done to Nikki when it pretended to be the demon that killed her family. It was looking for weaknesses, because Walden frightened and distracted would be a lot easier to take down. But she was frightened, she was distracted. Her body, her expertise, and her career as tools for this ruthless predator: it was an awful picture.

“Ready?” said Old Faithful.

“Yes,” Walden said.

It pounced.

Not physically. Charlie’s body stayed where it was, grinning. But Walden went to one knee under the force of a solid wave of magic that roared across the airy kitchen towards her. It went through her shield like tissue paper. She recast it, frantically fast, and felt only the aftereffect of whatever that attack had been, like the prickling of a thousand tiny knives. Very nasty.

Magical combat was simply not Walden’s area of expertise. It was what Marshals did, with their shining swords and their rune-marked vambraces, or else it was a personal enthusiasm pursued by academic specialists in evocation. Walden’s style of doing magic was almost exactly opposite. Invocation, in its purest form, was meticulous and elegant and beautiful and slow. It was worked out at a desk beforehand, or memorised as a series of complex, overlapping annotated diagrams. It was satisfying, challenging, intellectual, and totally unhelpful when a giant demon was trying to stab you with thousands of sorcerous knives.

She had already tired herself out shutting down Nikki’s pentagram and getting the two sixth formers out of that trap. She regretted, now, levitating Will earlier; she should have let Laura carry him. She had not reached this far into her own reserves in years. A schoolteacher—even a schoolteacher teaching A-level Invocation—just did not need to use this much power this fast. No point trying to get fancy. Walden struggled upright from her half-kneeling crouch and spoke a banishment, one she’d written herself, years ago now. The syllables echoed off her tongue and took on shuddering form in the air of the demonic plane, each a solid little ball of magical force.

Old Faithful took them all to the face and shoulders and then shook itself hard. Walden had seen Charlie react that way to getting caught coatless in February sleet: Ooh, ow, feck, and then shaking himself like a dog when they got indoors, breaking into laughter. There was no laughter now, but no caution either. That banishment really hadn’t bothered the demon at all. Walden revised her estimate of its size upwards: she’d assumed tenth order, but this was eleventh, definitely, and maybe tending towards the twelfth. She knew that spell would have a destabilising effect on a tenth-order demon. She’d developed it for exactly that purpose.