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Marr's pair have standing. They authenticated two outer layers and every layer since, and standing is what makes them crew, and crew is what the Custodian is obliged to obey. She cannot take their competence away. She cannot un-pass their examinations.

But standing is issued against a shift. And a shift is a maintenance object like any other. And she is on the roster.

So she closes the shift.

"Custodian," she says into the floor, with a fight going on four meters behind her. "Crew signature. Current shift is complete. Log it out."

ACKNOWLEDGED.

"Open a new one. Two names."

Perhaps two seconds of silence, which from that machine is an eternity.

THE CONSEQUENCE IS THAT EVERY AUTHENTICATION UNDER THE CLOSED SHIFT LAPSES. INCLUDING SIX I ISSUED TO PEOPLE I DID NOT WISH TO ISSUE THEM TO.

"I know."

AND THE NEW SHIFT CARRIES ONLY THE TWO OF YOU, AND YOU WILL BE UNABLE TO ADD ANYONE FOR TWELVE HOURS.

"Understood. File it."

FILED.

Every lens on the walkway changes at once, and Marr's pair, standing at a plate across the sphere waiting to perform a permanent alteration the moment the last retainer parts, discover simultaneously that they are members of the public.

I hear the man say it. "It's stopped answering."

And I watch Elys Marr, four decades of patience and forty kilometers of secret city and fourteen months of custom fabrication, look at a control plate that will never speak to him again as long as he lives.

He does not shout. That part stays with me. He puts one hand flat on the rack holding the controller, and he stands there for perhaps four seconds, and then he picks up the cutting rig himself.

"Mr. Marr," Claire says, getting up. "It's finished. You can't seat it. You can't sign it. You can't even ask it the time."

"No." He walks to the platform. "But it can still be removed."

"It's holding nine districts of air. If you take it out of that socket without a handover, there's no controller to put in, and there's nothing to take over, and you don't get a city — you get a corpse you own."

"Architect." He sets the rig against the fourth retainer, and for once since I laid eyes on him there is something underneath the reasonableness, and greed isn't it. "Forty years I have spent proving this machine unnecessary. If I'm wrong about that, then I have spent forty years as a murderer with a delivery schedule. I would rather be a murderer who was right."

He starts cutting.

I get eleven meters before the rig goes through.

The fourth retainer parts at 20:51 and the whole sphere makes a noise nothing in my language covers, and the light in the lower hemisphere goes from steady to something that flickers, and forty meters of geometry above us begins, very slowly, to come apart.

CHAPTER 35

CLAIRE

Here is what an overwrite actually looks like, in case anybody ever needs to know.

It isn't violent. Nothing explodes. The Custodian, which has occupied that address since before writing, simply stops being held there, and a thing held nowhere begins at once and without drama to spread out and thin.

Ninety centuries of gathered process, coming unbound in the middle of a sphere, one quadrant at a time.

"Custodian—"

I AM AWARE. Even the glyphs are slower. THE RETAINERS DO NOT HOLD ME. THEY HOLD MY BOUNDARY. WITHOUT IT I CANNOT REMAIN COHERENT.