“No one cares about Bowden,” he said at last. “Not Ul Qoma, not Besźel, not Canada, not Orciny. But yes, we’ll present a form to them. Maybe, after he dumped Mahalia, he got back into Ul Qoma by Breach.”

“He didn’t dump her; it was Yorj—” I said.

“Maybe that’s how he did it,” Ashil continued. “We’ll see. Maybe we’ll push him into Besźel and pull him back to Ul Qoma. If we say he breached, he breached.” I looked at him.

Mahalia was gone. Her body had at last gone home. Ashil told me on the day her parents held her funeral.

Sear and Core had not left Besźel. It would risk attention to pull out after the creeping, confused revelations of Buric’s behaviour. The company and its tech arm had come up, but the chains of connection were vague. Buric’s possible contact was a regrettable unknown, and mistakes had been made, safeguards were being put in place. There were rumours that CorIntech would be sold.

Ashil and I went by tram, by Metro, by bus, by taxi, we walked. He threaded us like a suture in and out of Besźel and Ul Qoma.

“What about my breach?” I asked it at last. We had both been waiting for days. I did not ask When do I get to go back home?  We took the funicular to the top of the park named for it, in Besźel at least.

“If he’d had an up-to-date map of Besźel you’d never have found her,” Ashil said. “Orciny.” He shook his head.

“Do you see any children in the Breach?” he said. “How would that work—if any were born?”

“They must be,” I interrupted, but he talked over me. “—how could they live here?” The clouds over the cities were dramatic, and I watched them, rather than him, and pictured children given up. “You know how I was made Breach,” he suddenly said.

“When do I get to go home?” I said pointlessly. He even smiled at that.

“You did an excellent job. You’ve seen how we work. Nowhere else works like the cities,” he said. “It’s not just us keeping them apart. It’s everyone in Besźel and everyone in Ul Qoma. Every minute, every day. We’re only the last ditch: it’s everyone in the cities who does most of the work. It works because you don’t blink. That’s why unseeing and unsensing are so vital. No one can admit it doesn’t work. So if you don’t admit it, it does. But if you breach, even if it’s not your fault, for more than the shortest time … you can’t come back from that.”

“Accidents. Road accidents, fires, inadvertent breaches …”

“Yes. Of course. If you race to get out again. If that’s your response to the Breach, then maybe you’ve got a chance. But even then you’re in trouble. And if it’s any longer than a moment, you can’t get out again. You’ll never unsee again. Most people who breach, well, you’ll find out about our sanctions soon. But there is another possibility, very occasionally.

“What do you know about the British Navy?” Ashil said. “A few centuries ago?” I looked at him. “I was recruited the same as everyone else in Breach. None of us were born here. We were all once in one place or the other. All of us breached once.”

There were many minutes of silence between us. “There are people I’d like to call,” I said.

HE WAS RIGHT. I imagined myself in Besźel now, unseeing the Ul Qoma of the crosshatched terrain. Living in half of the space. Unseeing all the people and the architecture and vehicles and the everything in and among which I had lived. I could pretend, perhaps, at best, but something would happen, and Breach would know.

“It was a big case,” he said. “The biggest ever. You’ll never have so big a case again.”

“I’m a detective,” I said. “Jesus. Do I have any choice?”

“Of course,” he said. “You’re here. There’s Breach, and there’s those who breach, those to whom we happen.” He did not look at me but out over the overlapping cities.

“Are any volunteers?”

“Volunteering’s an early and strong indication that you’re not suited,” he said.

We walked towards my old flat, my press-ganger and I.

“Can I say good-bye to anyone? There are people I want to—”

“No,” he said. We walked.

“I’m a detective,” I said again. “Not a, whatever. I don’t work like you do.”

“That’s what we want. That’s why we were so glad you breached. Times are changing.”

So the methods may not be so unfamiliar as I feared. There may be others who proceed the traditional Breach way, the levering of intimidation, that self-styling as a night-fear, while I—using the siphoned-off information we filch online, the bugged phone calls from both cities, the networks of informants, the powers beyond any law, the centuries of fear, yes, too, sometimes, the intimations of other powers beyond us, of unknown shapes, that we are only avatars—was to investigate, as I have investigated for years. A new broom. Every office needs one. There’s a humour to the situation.

“I want to see Sariska. You know who she is, I guess. And Biszaya. I want to talk to Corwi, and Dhatt. To say good-bye at least.”

He was quiet for a while. “You can’t talk to them. This is how we work. If we don’t have that, we don’t have anything. But you can see them. If you stay out of sight.”

We compromised. I wrote letters to my erstwhile lovers. Handwritten and delivered by hand, but not by my hand. I did not tell Sariska or Biszaya anything but that I would miss them. I was not just being kind.

My colleagues I came close to, and though I did not speak to them, both of them could see me. But Dhatt in Ul Qoma, and later Corwi in Besźel, could tell I was not, or not totally, or not only, in their city. They did not speak to me. They would not risk it.

Dhatt I saw as he emerged from his office. He stopped short at the sight of me. I stood by a hoarding outside an Ul Qoman office, with my head down so he could tell it was me but not my expression. I raised my hand to him. He hesitated a long time then spread his fingers, a waveless wave. I backed into the shadows. He walked away first.

Corwi was at a café. She was in Besźel’s Ul Qomatown. She made me smile. I watched her drinking her creamy Ul Qoman tea in the establishment I had shown her. I watched her from the shade of an alley for several seconds before I realised that she was looking right at me, that she knew I was there. It was she who said good-bye to me, with a raised cup, tipped in salute. I mouthed at her, though even she could not have seen it, thanks, and good-bye.

I have a great deal to learn, and no choice but to learn it, or to go rogue, and there is no one hunted like a Breach renegade. So, not ready for that or the revenge of my new community of bare, extracity lives, I make my choice of those two nonchoices. My task is changed: not to uphold the law, or another law, but to maintain the skin that keeps law in place. Two laws in two places, in fact.

That is the end of the case of Orciny and the archaeologists, the last case of Inspector Tyador Borlú of the Besźel Extreme Crime Squad. Inspector Tyador Borlú is gone. I sign off Tye, avatar of Breach, following my mentor on my probation out of Besźel and out of Ul Qoma. We are all philosophers here where I am, and we debate among many other things the question of where it is that we live. On that issue I am a liberal. I live in the interstice yes, but I live in both the city and the city.