The Farmer attack, if it was going to happen at all, would have to happen soon. Until then there was nothing to do but look at the sky, and it was obvious from the dire angle of the Arch that we were at the critical point of the passage. The Vox Archipelago was big enough that some of it must already be past the midway point. But that didn’t matter—Vox would transit all at once or not at all. An Arch—and this truth had been established many centuries ago—was more like an intelligent filter than a door. Back when this Arch was working it had been able to distinguish between a bird in flight and a boat in the water: send the boat from Earth to Equatoria but leave the bird behind. That’s not a simple decision. The Arch had to be able to identify human beings and their works while ignoring the countless other living creatures who inhabited (or had once inhabited) both worlds. Crossing an Arch, in other words, wasn’t a mechanistic process. The Arch looked at you, evaluated you, accepted you or rejected you.

The most likely outcome was that we wouldn’t be admitted to Old Earth at all. But I was more afraid of the other possibility. Even before the Arch stopped working, the Earth had changed beyond anything Turk would have recognized. The last refugees from the polar cities had described drastic shifts in the oceanic chemocline, H2S boiling out of hopelessly eutrophied offshore dead zones, massive and sudden dry-land extinctions

I closed my eyes and drifted into the dazed semiconsciousness that passes for sleep when you’re exhausted and hungry and in pain. Periodically I opened my eyes and looked at Turk where he lay in the shadows with his arms bound behind him. He was nothing like what Treya had once pictured as an emissary from the Hypotheticals. He looked exactly like what he was—a rootless drifter, no longer young and worn almost beyond endurance.

I guessed he was dreaming, because he moaned from time to time.

Maybe I dreamed, too.

What woke me next—still deep in that long night—was a sound so loud it cut the darkness like a knife. It was a deep-throated hooting, continuous and inhuman but familiar, familiar … dazed, I couldn’t place it at first; but when I recognized it I felt what I had not felt for many days: hope.

I kicked at Turk to rouse him. He opened his eyes and rolled upright, blinking.

“Listen!” I said. “You know what that is? It’s the alarm, Turk, it’s the call-in, the come-to-shelter,” struggling to translate Voxish words into ancient English, “it’s the fucking air-raid siren!”