“You are banned from squatting in my lobes and my hippocampus. I don’t want you pushing all the furniture around in there.”

Perhaps there was some tiny grain of sympathy in Harrow. She did not respond with a horrid laugh or a dark Ninth saying: she just flapped her hand. “Don’t have an aneurysm, Nav. I cannot and will not read your thoughts, control your body, or look at your most intimate memories. I don’t have the ability and I certainly don’t have the desire.”

“It’s for your protection, not mine,” said Gideon. “I imagined Crux’s butt once when I was twelve.”

Harrow ignored her. “Winnowing,” she said. “I’m a fool. It wants the wheat from among the chaff—or the signal from the noise, if you like. But why? Why can’t I just do it myself?”

She swayed lightly, and swabbed a pink line across her face with one sleeve. Her cultist paint was looking distinctly sepia, but she looked elated, grimly satisfied somehow.

“I now know how to complete this trial,” she said meditatively. “And we’ll do it—if I work out the connection and rethink what I know about possession theory, I can do it. Knowing what to work on was the battle, and now I know. But first, Griddle, I’m afraid I have to pass out.”

And she crumpled neatly back onto the floor. Pure sentiment found Gideon kicking out one leg to catch her. She ended up lightly punting her necromancer on the shoulder but assumed that it was the thought that counted.

15

“I’D DO A HELL of a lot better with a longsword,” Gideon said.

A few hours after, Harrowhark had woken up from her floor nap and accompanied her cavalier back to their quarters. She’d been all for trying again then and there, but it took Gideon one look at her slightly crossing eyes and shaky hands to nix that plan. Now they were back in their main, dark-panelled room, the noonday light filtering through the blinds in hot slats of white, with Gideon galumphing down bread and Harrow picking at crusts. The necromancer had woken up just as sour as ever, which gave Gideon some hope that everything back there had been a passing fit of insanity.

“Insinuation denied,” said Harrowhark. “You don’t have one”—sweet, that meant Harrow hadn’t successfully been through all her stuff—“and more importantly, you should do without. I never liked that cursed thing anyway; I always felt like it was judging me. If you require a two-handed sword every time the chips are down you’re worth nothing as my cavalier.”

“I still don’t get how this whole test is meant to work.”

The Reverend Daughter gave this consideration, for once. “All right. Let me—hmm. You know that a bone construct is animated by a necromantic theorem.”

“No way! I assumed you just thought super hard about bones until they happened.”

Ignoring this, Harrow continued: “This particular construct is animated by multiple theorems, all—woven together, in a sense. That enables it to do things normal constructs can’t possibly.”

“Like regenerate.”

“Yes. The way to destroy it is to unpick that tapestry, Nav, to pull on each thread in turn—in order—until the web gives way. Which would take me ten seconds, if I only had it at arm’s length.”

“Huh,” said Gideon, unwillingly starting to get it. “So I unpick it for you.”

“Only with my assistance. You are not a necromancer. You cannot see thanergetic signatures. I have to find the weak points, but I have to do it through your eyes, which is made infinitely more difficult by you waving a sword around the whole time while your brain—yells at me.”

Gideon opened her mouth to say My brain is always yelling at you, but was interrupted by a sharp rap on the door. The necromancer froze as though she were under attack, but this knock was followed by guttural hysterics of the kind that Gideon had heard before. The sound drifted off down the corridor accompanied by the hurried footsteps of two semiterrified teenagers. Jeannemary and what’s-his-face had shoved something underneath the door, and left.

She went to see what it was. It was a plain, heavy envelope—real paper, creamy brown. “Reverend Daughter Harrowhark Nonagesimus,” she read out loud. “Gideon the Ninth. Fan mail.”

“Give it to me. It might be a trap.”

Gideon ignored this, as it was quite likely Harrow would toss the thing out the window rather than give it a chance. She also ignored Harrow’s lemon-pucker scowl as she withdrew a piece of flimsy—less impressive than the envelope, but who barring the Emperor would use real paper for a letter—and read aloud its contents.

LADY ABIGAIL PENT AND SIR MAGNUS QUINN

IN CELEBRATION OF THEIR ELEVENTH WEDDING ANNIVERSARY

PRESENT THEIR COMPLIMENTS TO THE HEIR AND CAVALIER PRIMARY OF THE NINTH HOUSE

AND REQUEST THE HONOUR OF THEIR COMPANY THIS EVENING.

DINNER TO BE SERVED AT SEVEN O’CLOCK.

Underneath in hasty but still beautifully-formed handwriting was another note:

Don’t be affrighted by the wording, Abigail can’t resist a formal invitation, at home am practically issued one for breakfast. Not at all a serious function & would be deeply pleased if you could both see fit to come. I will make dessert, can reassure you I cook better than I duel.—M.

Harrow said, “No.”

“I want to go,” said Gideon.

“This sounds impossibly vapid.”

“I want to eat a dessert.”

“It occurs to me,” said Harrow, drumming her fingers, “that during a single dinner the deaths of multiple House scions could be assured by one clever pair, a bottle of poison, and then—suddenly, the Fifth House’s primacy is assured. And all because you wanted a sweet.”

“This is a formal invitation to the Ninth House, not just you and me,” said Gideon, more cunningly, “and being dyed-in-the-wool traditionalists, shouldn’t we make a teeny weeny appearance? It’ll look rude if we don’t go. We can extrapolate heaps from whoever doesn’t come, and everyone will, to be polite. Politics. Diplomacy. I’ll eat yours if you don’t want it.”

The necromancer lapsed into brooding. “But this delays finishing the trial,” she complained finally, “and wastes an evening in which Sextus can get ahead of us at his leisure.”

“Bet you Palamedes will be there. We can do the trial afterward. And I’ll be so good. I’ll be silent and Ninth and melancholy. The sight will astound and stimulate you.”

“Nav, you are a hog.”

But that meant they were going to go. Gideon reflected on her unexpected victory as she stared in the mirror, idly counting the pimples cropping up as the result of repeated slathers of cult paint. The atmosphere was—relaxed, in this strange and waiting way, like the time she’d got a sedative and knew a nun was coming to whip out her tonsils. She and Nonagesimus were both waiting for the knife. She had never known Harrow to be so malleable, nor to go such a long time without raking her claws across Gideon’s internal tender spots. Maybe the Lyctor trials were having a mellowing effect on her.

No, that was too much to hope for. Harrowhark was pleased because everything was coming up Harrowhark—she was glutted on getting her own way, and the moment that glow wore off the knives would come out again. Gideon couldn’t trust Harrow. There was always some angle. There was always some shackle closing on you before you could even see it, and you’d only know when she turned the key. But then—