The cut-off groan Todd let out as he slid out from under the brassy bulk of the thaumic engine and sat up would probably have been a yell of pain from someone else. Todd showing any sign of being made of something less than solid oak was alarming. His shoulder-length grey hair was lank with sweat and dust. This was one of the few parts of the school that Premises could not access to bring in a vacuum cleaner. Walden had discovered, in the last two days, that Todd had been meticulously sweeping and polishing in here himself. He was ashamed—ashamed!—that in the last few years he’d stopped forcing himself to get down on his knees with dustpan and brush in order to get at the grimy residue that built up underneath the engines at the back.

Walden was the one who should have been ashamed. She just hadn’t thought about how the thaumic engines were staying clean. Two people ever went in, and Walden hadn’t been sweeping. She should have been. She was a lot younger than Todd.

She eventually managed to coax him out and send him off to the canteen, though only by the underhanded expedient of displaying the kind of fluttery feminine concern that felt like a ridiculous mask to her, but allowed Todd to be gruff and tough about how brutally hard they were working. Then she got back to her own job, picking up where she’d left off, going through the diagnostic readouts which were stamped onto a long thin roll of paper by an immensely slow punch-card system installed as an upgrade in about 1910. It was achingly dull. The readouts followed no current standard of magical analysis; they were masses of badly organised data, most of it useless, the sort of thing you would have fed through a computer to analyse if this system had been designed at any point in Walden’s lifetime. Without the Phoenix in the back of her thoughts providing sharp, interested commentary, it would have been impossible to focus. As it was, Walden was so completely absorbed that she let out a small scream when she realised someone else was in the room.

“Didn’t mean to scare you,” said Mark. “How’s it going?”

“Nothing yet,” Walden said. “How was your patrol?”

“Still no sign of anything big moving in,” Mark said. That was the fear that lay under all Walden’s other fears, the danger Laura had pointed out months ago: the dreadfully tasty target that Chetwood represented to a new higher demon, a second Old Faithful. They’d survived an incursion on that level with no casualties once. They’d been very, very lucky.

“You look frazzled,” Mark said. “Up for some relaxation?”

“Mark,” said Walden.

Yes, all right, so they’d kept going.