The walls were covered with engravings. Collingdale assigned one of his people to record as many of them as she could. Some of it was symbolic, much was graphic, usually with bucolic themes, leaves and stems and branches, all of which, when the sun came back, might grow on this world again.

Stairways and shafts rose high into the structure and descended to lower floors, which were encased in ice. “But that might be a huge piece of good luck,” Collingdale told Ava MacAvoy, who looked unusually attractive in the reflected light. “It should survive the cloud, whatever happens to the rest of the city.”

They went back outside. It was time to leave, but Collingdale delayed, taking more pictures, recording everything. Ava and Riley and the others had to pull him away.

The cloud was setting by then, and Collingdale wished it was possible to halt the planet on its axis, keep the other side between the omega and the towers. Hide the city.

Damn you.

He stood facing it, as if he would have held it off by sheer will.

Ava took his arm. “Come on, Dave,” she said. “It’s getting late.”

THEY RETREATED TO the dome, which had served as their base for the better part of a month. A lander waited beside it. The dome was small, cramped, uncomfortable. They’d brought out too many people, and could in fact have brought several shiploads more. Everyone had wanted to come to Moonlight. The Academy, under time pressure, had tried to accommodate the requests as best it could. It should have said no. That was partly Collingdale’s own fault for not demanding they cut things off.

They’d filled the dome with artifacts and shipped them topside to the al-Jahani, which now carried a treasure trove of mugs and plates and table lamps and electronic gear, and materials far more esoteric, objects whose function defied analysis. Other pieces were now being loaded. There was more than the lander could handle, but they’d stacked the rest in the dome, hoping that it would be safe there.