"Then I suppose Isaac will become a datum too," Mrs. Rebka said, suddenly meek, and here, Diane thought, was the heart of her revealed. Mrs. Rebka knew that Isaac would die, that there was no other possible outcome of his transaction with the Hypotheticals, and some part of her had accepted that dreadful truth.

"As he probably remembers Jason Lawton," Sulean Moi said. "Isn't that the question on your mind, Diane?"

Hateful in her perceptiveness, this Martian hag. Doomed to exile from her planet, her people, even her Fourthness. She was steeped in bitterness. Worse, she was right. It was the question Diane had dared not ask. "Maybe I'd rather not know."

"And Dr. Dvali wouldn't stand for it. He would prefer to keep Isaac's epiphanies to himself. But Dr. Dvali isn't here."

"That doesn't matter," Diane said, faintly panicky.

"Isaac," Sulean Moi said.

"Stop," Mrs. Rebka said.

"Isaac, can you hear me?"

Mrs. Rebka said Stop again, but Isaac's voice came faintly, a whisper: "Yes."

"Isaac," Sulean Moi said, "do you remember Jason Lawton?"

Please, no, Diane thought.

But the boy said, "Yes."

"And what would he say, if he were here?"

Isaac cleared his throat, a moist, froggy sound.

"He would say, 'Hello, Diane.' He would say—"

"No more," Diane begged. "Please."

"He would say, 'Be careful, Diane.' Because it's about to happen. The last thing."

What last thing? But there wasn't even time to pose the question before the last thing came up from the limestone and bedrock far underground. It shook the building, it rocked the floor, it quenched all thought, and it didn't stop.

CHAPTER TWENTY-SEVEN

Only Isaac saw it happening, because only Isaac had eyes that could see it. He could see many things, few of which he had described even to Mrs. Rebka or Sulean Moi, his most trusted friends.

For instance, he could see himself. He saw himself more clearly than ever before in the absolute darkness of the buried stockroom. Not his body exactly, but when he looked down he could see the silver skein of the Hypothetical presence inside him. It shared his nervous system, made glowing traceries of ever-finer filaments joined in bundles to the shimmering rod of his spine. Had the others been able to see him this way they probably would have been horrified. Some fraction of Isaac, the merely human part, was also horrified. But that voice was a diminishing presence, and a dissenting voice thought he was beautiful. He looked like electricity. He looked like fireworks.

The women—Mrs. Rebka, Sulean Moi, Diane—were also visible to him, but they shone with a much fainter light. Isaac guessed the Fourth treatment had done that to them, that it had infected them with a little bit (but only a little bit) of Hypothetical life. It was as if they were timid lamps in a fog, while Isaac…

Isaac was a searchlight, glaring.

And he could see other things, too, beyond the walls.