President Lomax was succeeded by President Hughes and then by President Chaykin, but they were all veterans of the same Spin-era politics. They saw Martian biotech as the new atomic bomb, at least potentially, and for now it was all theirs, a proprietary threat. Lomax's first diplomatic dispatch to the government of the Five Republics had been a request to withhold biotech information from uncoded Martian broadcasts to Earth. He had justified the request with plausible arguments about the effect such technology might have on a politically divided and often violent world—he cited the death of Wun Ngo Wen as an example—and so far the Martians had been playing along.

But even this sanitized contact with Mars had sewn some discord. The egalitarian economics of the Five Republics had made Wun Ngo Wen a sort of posthumous mascot to the new global labor movement. (It was jarring to see Wun's face on placards carried by garment workers in Asian factory zones or chipsocket fillers from Central American maquiladoras— but I doubt it would have displeased him.)

* * * * *

Diane crossed the border to attend E.D.'s funeral eleven years almost to the day after I rescued her from the Condon ranch.

We had heard of his death in the news. The obituary mentioned in passing that E.D.'s ex-wife Carol had predeceased him by six months, another sad shock. Carol had stopped taking our calls almost a decade ago. Too dangerous, she said. It was enough just knowing we were safe. And there was nothing, really, to say.

(Diane visited her mother's grave while she was in D.C. What saddened her the most, she said, was that Carol's life had been so incomplete: a verb without an object, an anonymous letter, misunderstood for the want of a signature. "I don't miss her as much as I miss what she might have been.")

At E.D.'s memorial service Diane was careful not to identify herself. Too many of E.D.'s government cronies were present, including the attorney general and the sitting vice president. But her attention was drawn to an anonymous woman in the pews, who was sneaking reciprocal glances at Diane: "I knew she was a Fourth," Diane said. "I can't say exactly how. The way she held herself, the sort of ageless look she had—but more than that; it was like a signal went back and forth between us." And when the ceremony was over Diane approached the woman and asked how she had known E.D.

"I didn't know him," the woman said, "not really. I did a research stint at Perihelion at one time, back in Jason Lawton's day. My name is Sylvia Tucker."

The name rang a bell when Diane repeated it to me. Sylvia Tucker was one of the anthropologists who had worked with Wun Ngo Wen at the Florida compound. She had been friendlier than most of the hired academics and it was possible Jase had confided in her.

"We exchanged e-mail addresses," Diane said. "Neither of us said the word 'Fourth.' But we both knew. I'm certain of it."

No correspondence ensued, but every once in a while Diane received digital press clippings from Sylvia Tucker's address, concerning, for instance:

An industrial chemist in Denver arrested on a security writ and detained indefinitely.

A geriatric clinic in Mexico City closed by federal order.

A University of California sociology professor killed in a fire, "arson suspected."

And so on.

I had been careful not to keep a list of the names and addresses to which Jason had addressed his final packages, nor had I memorized them. But some of the names in the articles seemed plausibly familiar.

"She's telling us they're being hunted," Diane said. "The government is hunting Fourths."

We spent a month debating what we would do if we attracted the same kind of attention. Given the global security apparatus Lomax and his heirs had set up, where would we run?

But there was really only one plausible answer. Only one place where the apparatus failed to operate and where the surveillance was wholly blind. So we made our plans—these passports, that bank account, this route through Europe to South Asia—and set them aside until we needed them.

Then Diane received a final communication from Sylvia Tucker, a single word:

Go, it said.

And we went.

* * * * *

On the last flight of the trip, coming into Sumatra by air, Diane said, "Are you sure you want to do this?"

I had made the decision days ago, during a layover in Amsterdam, when we were still worried that we might have been followed, that our passports might have been flagged, that our supply of Martian pharmaceuticals might yet be confiscated.

"Yes," I said. "Now. Before we cross over."

"Are you sure?"

"As sure as I'll ever be."

No, not sure. But willing. Willing, finally, to lose what might be lost, willing to embrace what might be gained.

So we rented a room on the third floor of a colonial-style hotel in Padang where we wouldn't be noticed for a while. We all fall, I told myself, and we all land somewhere.

NORTH OF ANYWHERE

Half an hour before the transit of the Arch, an hour after dark, we came across En in the crew dining room. One of the crewmen had given him a sheet of brown paper and a few stubby crayons to keep him busy.

He seemed relieved to see us. He was worried about the transit, he said. He pushed his glasses up his nose—wincing when his thumb brushed the bruise Jala had left on his cheek—and asked me what it would be like.

"I don't know," I said. "I've never crossed."

"Will we know when it happens?"

"According to the crew, the sky gets a little strange. And just when the crossing happens, when we're balanced between the old world and the new world, the compass needle swings around, north for south. And on the bridge they sound the ship's horn. You'll know."

"Traveling a long way," En said. "In a short time."

That was undeniably true. The Arch—our "side" of it, anyway—had been physically dragged across interstellar space, presumably at something less than the speed of light, before it was dropped from orbit. But the Hypotheticals had had eons of Spin time to do the dragging. They could conceivably have bridged any distance shy of three billion light-years. And even a fraction of that would be a numbing, barely comprehensible distance.

"Makes you wonder," Diane said, "why they went to so much trouble."

"According to Jason—"

"I know. The Hypotheticals want to preserve us from extinction, so we can make something more complex of ourselves. But it just begs the question. Why do they want that? What do they expect from us?"

En ignored our philosophizing. "And after we cross—"

"After that," I told him, "it's a day's cruise to Port Magellan."

He smiled at the prospect.

I exchanged a look with Diane. She had introduced herself to En two days ago and they were already friends. She had been reading to him from a book of English children's stories out of the ship's library. (She had even quoted Housman to him: The infant child is not aware … "I don't like that one," En had said.)

He showed us his drawing, pictures of animals he must have seen in video footage from the plains of Equatoria, long-necked beasts with pensive eyes and tiger-striped coats.

"They're beautiful," Diane said.

En nodded solemnly. We left him to his work and headed up on deck.

* * * * *

The night sky was clear and the peak of the Arch was directly overhead now, reflecting a last glimmer of light. It showed no curvature at all. From this angle it was a pure Euclidean line, an elementary number (1) or noun (I).

We stood by the railing as close as we could get to the prow of the ship. Wind tugged at our clothes and hair. The ship's flags snapped briskly and a restless sea gave back fractured images of the ship's running lights.

"Do you have it?" Diane asked.