The adept’s lips curled back, showing little slashes of swollen pink through the grey. “Yes,” she said. “Yes, I was dicking around in the basement. You didn’t need to get involved. You did just what I was afraid you would do, which was to remove me from a situation that I didn’t need to be removed from.”

“Didn’t need—? What, you were having a nap of your own free will?”

“I was recuperating—”

“Balls you were.”

Harrow opened her eyes. Her voice rose, cracking with tension: “The Sixth House, Griddle! Do you know how difficult it is to stay ahead of Palamedes Sextus? Didn’t I tell you to keep your pneumatic mouth shut? I would have been fine; I’d fainted; I was resting.”

“And how I’m meant to know that,” said Gideon heavily, “I’ve got no idea. I want answers, and I want them yesterday.”

The whites around Harrow’s eyes were pink and inflamed, probably from too little rest and too much fainting. She closed them again and her head came down, heavy, back to the bed. Her dead black hair fell in lank and tangled hanks on the pillow. She looked flat and tired.

“I’m not having this conversation with you,” she said finally.

“Yeah, you are,” said Gideon. “I took my key ring back, so if you ever want to dick around in that basement again you’ll have a hell of a time getting back in there.”

The necromancer’s lips pursed in a sour, thin line that was obviously meant to show iron resolve but simply showed a bunch of mouth scabs. “That’s easily contrived. You can’t stay awake forever.”

“Quit bluffing, Nonagesimus! Quit acting like I was the one who messed up here! You haven’t spoken more than twenty words to me since we arrived, you’ve kept me totally in the dark, and yet I’ve done every single thing you ever goddamned asked of me no matter what it was—okay, I did come to find you, nearly every single thing—but I kept my head down and I didn’t start shit. So if you could see your way to being even ten percent less salty with me, that’d be just terrific.”

Silence spread between them. The iron resolve on that scabrous mouth seemed to waver, just a little bit. Gideon added, “And don’t push me. The places where I can and would stick this thing for safekeeping would astonish you.”

“Puke,” murmured Harrow. And: “Give me the water, Griddle.”

She could barely drink it. She lifted her head for a few spluttering sips, then lay back down, eyelashes brushing eyelids again. For a couple of moments Gideon thought she had gone back to sleep: but then Harrow stirred and said colourlessly: “I’d hardly call sucker-punching the Third cavalier keeping your head down.”

“You disapprove?”

“What? Hardly,” said Harrow, unexpectedly. “You should have finished the job. On the other hand, dallying with the Seventh House is the act of the naif or the fool, or both. What part of Don’t talk to anybody did you not register—”

“Dulcinea Septimus is dying,” said Gideon. “Give me a break.”

Harrow said, “She picked an interesting place to die.”

“What are you doing, where are you doing it, why are you doing it? Start talking, Reverend Daughter.”

They stared each other down, both similarly mulish. Harrow had taken another swig of water and was slowly swilling it around in her cheeks, apparently thinking hard. Gideon dropped back to sit on the gently sagging dresser, and she waited. Her necromancer’s mouth was still puckered up with a sourness that would’ve impressed a lemon, but she asked abruptly:

“What did the priest specify was the only rule, the first day we were here?”

“You’re not very good at I’m Asking the Questions Now, Bitch, are you,” said Gideon.

“This is going somewhere. Answer me.”

Gideon resented the answer me, but she begrudgingly cast her mind back through a montage of rotting furniture, assholes, and astringent tea. “Teacher?” she said. “Uh—the door thing. We weren’t to go through any locked door.”

“More specifically, we weren’t to go through a locked door without permission. The old man’s a pain in the neck, but he was giving us a clue—take a look at this.”

Harrow appeared to be thawing to her subject. She thrashed feebly trying to sit up, but before this could soften Gideon’s concrete heart she got cross and snapped two bone chips out of her sleeve. Harrow pressed them against the dank arm of the four-poster bed, and out sprung bony arms that hauled her up into a sitting position. They dragged her flush with the headboard, and a shower of dust trickled down from the enormous cloth drapes. Harrow sneezed fretfully, half of it blood.

She searched about in her robes and came up with a thick little book bound in cracked, blackened stuff, with the awful orange tone of tanned human leather. The book was a thousand pages thick, maybe a million. “Light,” she demanded, and Gideon nudged the lamp forward. “Good. Look here.”

Harrow flicked through pages with scabby fingers until she had opened the squat book midway, showing three sets of angular diagrams. They appeared to be numerous overlapping squares, with lines coming out at odd angles and a scrawl of notes or numbers bumping up against the lines. The writing was minute and spidery: the squares mazelike and innumerable. Gideon realised after a moment that she was looking at an architectural drawing, and that it was an architectural drawing of Canaan House. It was scribbled thickly with cross marks.

“I’ve divided Canaan House into its three most significant levels, but that’s not quite accurate. The central floor is more of a mezzanine providing access to the top and bottom floors. The terraces are sections in and of themselves, but they’re not important for what I’m identifying here. Each X denotes a door. Current count is seven hundred and seventy-five, and Griddle—only six are locked. The first two hundred doors I identified—”

“You spent this whole time counting doors?”

“This calls for rigor, Nav.”

“Maybe rigor … mortis,” said Gideon, who assumed that puns were funny automatically.

“The first two hundred doors I identified,” Harrow repeated, through gritted teeth, “included the access hatch to the lower area of Canaan House. My method was to start at the bottom and go up as far as I could from a static starting point. There are two lock-points here, at X-22 and X-155. X-155 is the hatch, X-22 is another door. I went to Teacher and asked permission to enter both. He agreed to let me through the hatch if I could provide a safe place for the key, but said that X-22 didn’t belong to him and that he couldn’t in good conscience give permission. All the while he was winking at me so hard that I thought he had suffered a stroke.”

Despite everything, Gideon was starting to get interested. “Okay. Then what?”

“Then in the morning I retrieved the key ring,” said Harrow.

“Hold up, hold up. My key ring, more correctly, but let’s be clear here, you’d counted two hundred doors before the first morning?”

“A head start,” said her necromancer, “is the only advantage one can claim by choice. My other advantage is in workforce. In this case I’m fairly sure that Sextus started a mere two hours after me, and that Eighth House zealot not long after.”