“Restore only the logs that do not give the mice any control or influence on this ship.”

“That will leave gaps in our data,” said the expendable.

“Gaps that will be alleviated after we return from our attempt to change the future,” said Ram Odin.

“Good job,” said the expendable. “You finally asked the right questions.” He turned to Noxon. “Beginning with you.”

“I appreciate your congratulations,” said Noxon. “But I’m not sure I believe you. How can we be sure the mice didn’t instruct you merely to pretend to follow Ram’s instructions, so that we’d leave?”

“We aren’t infinitely devious,” said a mouse from inside the box.

“You do understand why I will never trust you,” said Noxon.

“That is a very wise decision,” said the mouse. “And one that will cost us dearly, I’m afraid.”

“Maybe,” said Noxon. “And maybe not. That’s still up to you.”

“You mean you’re not going to kill them even now?” asked Ram Odin.

“I’m not,” said Noxon. “But I’m also not leaving them with the ship.”

Noxon carried the mice aboard the flyer, but left the expendable on the ship. Ram and Noxon then had the flyer take them down to Earth, to a tectonically stable plateau in what would one day be Peru. Someday, the Nazca lines would be marked out by human inhabitants. But right now, the ground was smooth.

Since humans hadn’t yet spread to this area, it was simple enough to pick their spot, pile up a few stones, and then find an animal’s path to link to in order to get back to the target time at the beginning of this glacial maximum. At that point, a hundred thousand years in the past, Noxon, Ram Odin, and the expendable spent several days laying out an arrangement of stones large enough to be picked up by the instruments on an orbiting ship a few hundred kilometers up.

They buried the box of mice at one end of the stone figure they had created.

Then they went forward again about eighty thousand years, to the time when they had made that first small pile of stones. They checked to make sure that their large arrangement of stones had lasted for the intervening eighty thousand years. It had. It would be continuously visible from space.

They rode the flyer back up to the ship. Noxon made several huge jumps back in time until their large marker stopped being visible, then made much smaller jumps into the future until it finally showed up again.

They took the ship through atmospheric entry and landed it on a grassy plateau in Antarctica. It was hard to believe that in a few thousand years this spot would be under at least a hundred meters of ice, but the expendable assured them that the spot had been carefully noted and it was ideal for concealing a dead ship.