“Premature birth,” said Bean.

“And we can guess that statistically, half the eight babies should have the trait. Mendel’s law. Not ironclad, because randomness is involved. So there might be only three. Or five. Or more. Or this might be the only one. But the likeliest thing—”

“We know how probability works, Professor,” said Ferreira.

“I wanted to emphasize the uncertainty.”

“Believe me,” said Ferreira, “uncertainty is my life. Right now we’ve found either two dozen or nearly a hundred groups of women who gave birth within two weeks of Petra, and who moved at the same time as others in their group, since the day Volescu was arrested.”

“How can you not even know how many groups you have?” asked Bean.

“Selection criteria,” said Petra.

“If we divide them into groups that left within six hours of each other, then we get the higher total. If we divide them into groups that left within two days of each other, the lower total. Plus we can shift the timeframes and the groups also shift.”

“What about prematurity in the babies?”

“That supposes that the doctors are aware that the babies are premature,” said Ferreira. “Low birth weight is what we went for. We eliminated any babies that were higher than the low end of normal. Most of them will be premature. But not all.”

“And all of this,” said Petra, “depends on all the babies being on the same clock.”

“It’s all we can go on,” said Peter. “If it turns out that Anton’s Key doesn’t make them all trigger delivery after about the same gestation time…well, it’s no more of a problem than the fact that we don’t know when the other embryos were implanted.”

“Some of the embryos might have been implanted much more recently,” said Ferreira. “So we’re going to keep adding women to the database as they give birth to low-birthweight children and turn out to have moved at about the time Volescu was arrested. You realize how many variables there are that we don’t know? How many of the embryos have Anton’s Key. When they were implanted. If they were all implanted. If Volescu even had a deadman switch.”

“I thought you said he did.”

“He did,” said Ferreira. “We just don’t know what the switch was about. Maybe it was for release of the virus. Maybe for the mothers to move. Maybe both. Maybe neither.”

“A lot of things we don’t know,” said Bean. “Remarkable how little we got from Volescu’s computer.”

“He’s a careful man,” said Ferreira. “He knew perfectly well that he’d be caught someday, and his computer seized. We learned more than he could have imagined—but less than we had hoped.”

“Just keep looking,” said Petra. “Meanwhile, I have a baby-shaped suction cup to go attach to one of the tenderest parts of my body. Promise me that he won’t develop teeth early.”

“I don’t know,” said Bean. “I can’t remember not having them.”

“Thanks for the encouragement,” said Petra.