Deborah seemed so eager, but Noxon wondered how long that eagerness would last, in the boredom of slicing time. He thought of Param, who had sliced her way through so many hours, days, months of her youth, and the price she had paid for it. But Deborah has also paid a price; even with mechanical eyes, she has lacked many normal experiences. Perhaps her excitement over timeshaping is a welcome relief from an otherwise tedious life.

With this thought, Noxon looked at Deborah’s uncle, to see what he was making of her attitude.

Wheaton seemed to take Noxon’s glance as a cue to speak. “I’m glad you’re treating this scientific expedition so seriously,” he said. Sarcastically, of course, but also affectionately, or so it seemed to Noxon.

“They’re children,” said Ram. “Let them play.”

So Deborah passed most of the trans-Atlantic flight invisible, and Noxon made the time flow around them very quickly, so that the whole voyage only took a few dozen steps. But he returned her to regular time as the airport approach began, or the attendant would have noticed that she wasn’t there for the landing.

Once they were out of the airport and checked into a hotel, the first order of business was to figure out where their leap into the past should take place. Noxon’s pathfinding should allow them to pick exactly the spot they wanted—but there was a lot of Europe to search through. No point in going to all this trouble just to watch a Neanderthal take a long hike.

“I don’t know what a pathfinder can see,” said Wheaton. “But what I need is a time and place where Neanderthals were hunting bulls. Aurochs, probably, the giant Ice Age bovine.”

“But they weren’t entirely prehistoric,” said Deborah. “The last of them died in Poland in 1627. They seem to be ancestral to modern cattle. Both Asian zebus and Western taurines.”

“A fount of knowledge,” said Wheaton.

“I’m telling him that we’re not looking for cows,” said Deborah. “We’re looking for this.” She held out a tablet with a photo of an aurochs skeleton. “Note that the horns bend forward. That’s what led Father to guess that—”

“Hypothesize,” said Wheaton.

“Take a wild stab-in-the-dark guess,” Deborah recorrected him, “that the ancient Cretan depictions of bull-leaping show a sport that would have made far more sense with aurochsen rather than taurine bulls. You need to have those forward-­reaching horns if you’re going to grab them and leap onto the creature’s back.”