“I can’t believe you’re making me listen to something so disgusting,” said Param.

“Come on, you can’t tell me you never thought of it. I bet you tried it.”

“It was better when we were slicing time,” said Param. “We couldn’t talk then.”

“So if you don’t like what I think of to say, you say something.”

For a minute or two she remained silent. Then she spoke. “Thank you for not making me slice time when the mice knew where I’d be.”

“I think if they wanted us dead, they’d find a way, but sure, I could see why you didn’t want to do it. And I didn’t want you to run the risk either.”

“So thanks,” she said.

Umbo wanted to laugh. It was such a simple thing, saying thanks, but for her it was hard. Probably not hard to say thanks—just hard to say it to him.

“We’re going to have to slice time eventually, though,” said Param. “We didn’t pack a lunch.”

Something perverse in him made Umbo return to the previous subject. “Farting, too,” said Umbo. “Bet it completely fades before we can smell it, if you fart while slicing time. And no, I absolutely won’t believe it if you tell me you never did that while slicing time.”

“I never—”

“I have sisters,” said Umbo. “Girls fart and snore and belch and pee and all the really gross offenses. They just pretend they don’t, and expect everybody else to go along with the lie.”

Umbo expected Param to say something cutting. Or move away from him in disgust. Or disappear.

Instead she farted.

“Oh, you couldn’t wait till we time-sliced,” said Umbo.

“I don’t know what you’re talking about,” she said.

“I’m sure it was a collective fart from all the mice around us.”

“The mice broke wind?” she said. “How advanced of them. They have evolved to the level of boys. Still, that leaves a long way to go.”

Umbo smiled. Only a little. Maybe she wouldn’t notice. Wasn’t it amazing that she could say rude things one moment and it felt like hatred, and then say equally rude things the next moment, and it sounded like an offer of friendship.

They reached the boundary of the colony, as far as he remembered from the map in the flyer’s display. But he had a good memory for where things were, a good eye for landmarks. It was here.

“Tired?” asked Umbo.

“You woke me out of a sound sleep two years ago and I’ve been walking continuously since,” said Param. “How could I be tired?”

“Can you slice time in your sleep?”

Param hesitated. “Sometimes I wondered if I disappeared in my sleep. If it was such a reflex that I slept all night but only got a couple of hours’ sleep.”

“Tired all the time?”

“I wanted to go back to bed the moment I woke up.”

“Sounds like my mother,” said Umbo.

Param was about to say something, then thought better of it.

Something insulting about Umbo’s mother. And then a decision that this might be out of bounds.

Good call, Param.

“The mice know we’re here. So we could probably both sleep at once. But I’ll keep watch if it makes you feel safer.”

They were in the shadow of the woods now, and Umbo piled up this year’s leaves to make a large sleeping area without much work. Param lowered herself gracefully onto the leaves. Umbo sat up with his back leaning against a tree.

After a little while, Param moved herself closer to him. She held out one hand.

Umbo looked at the hand.

“Hold my hand,” she said. “In case I slice time in my sleep.”

Umbo took her hand.

It felt good.

In a few moments, she was snoring. She didn’t slice time. The mice left them alone. So instead of waking her to take her turn, Umbo eventually lay down beside her, still holding her hand, and caught some sleep as well. When he woke up, she was awake. But still holding his hand.

“Did I fart much?” asked Umbo.

“It’s been so long since you bathed, it’s hard to tell,” said Param.

“That was good,” said Umbo. “You’re getting good at this.”

“At insulting you? That’s not even a sport, Umbo,” she said. “It’s so easy.”

But because she called him by name, it didn’t sting. In fact, it made him feel kind of good.

Awake now, they took care of their morning ablutions, taking turns going down to the river, which was near enough to have been of use to the colony when it was new. Unlike the facemasks in Vadeshfold, the mantles in Larfold were larger and easy to avoid in the water.

Rested and a bit cleaner and emptier, Umbo mentioned that they should have thought of food, and Param said that she hardly thought of anything else, and then she sliced time again, days, weeks, until . . .

There was a flyer setting itself down a few hundred meters away.

Param and Umbo moved swiftly toward it. Of course, because they were in sliced time, the people around them moved even quicker.

They watched as the Visitors set up all kinds of equipment whose purpose Umbo couldn’t guess at. And very soon, mantled Larfolders began showing up to talk with the Visitors.

The Visitors looked like regular people. There were sharp differences between them—some with skin so light you might call it white, others so black it was blue. Far more variety than the rather uniform brown of the wallfolds they had visited so far.

Umbo decided this meant that on Earth, races that originated in one geographical area tended to marry within their tribe, while on Garden, everybody had intermarried so much within each wallfold that, because the colonies had been identical at startup, they all evolved into the same intermediate brown.

We won’t learn anything if we don’t talk to them, thought Umbo. That meant coming out of sliced time and taking things at a normal—and visible—pace.

Then there was a flurry of motion near the Visitors’ flyer, and Umbo realized what it was. Mice were scurrying up a bit of cable dangling from the ramp leading up to the flyer’s door.

Not all scurrying, though. Some of them moved downright sluggishly.

Why so slow?

Pregnant, he thought. More babies.

No. They wouldn’t want their babies to be born en route. It would be hard enough to conceal adults; younglings would be impossible to hide.

So why else might some mice be more sluggish than others in climbing the rope?

And then Umbo realized: They were sick.

Why would they send sick mice as their agents?

Because the sickness was the purpose of their stowing away.

The mice had created a disease of which they were themselves the vector. They would go to Earth and pass the disease to humans.

A crowd of Larfolders assembled. Umbo signaled a stop and Param slowed the movements of the people around them to a speed approaching normal.

One of the Visitors, a woman, was talking, and after a very short time, Umbo understood the language. She would speak a sentence, and then a Larfolder would translate for her. How does the interpreter know the Visitors’ language, he wondered. Then Umbo remembered that the Larfolders had held on to the ancient language with some stubbornness. And because they could ordinarily speak only on shore, they spoke more rarely, and so their language would evolve less. Maybe it was still very similar to whatever the Earth people spoke.

“I know what the mice are doing,” whispered Umbo.

“Sneaking on board the ship?

“With a disease,” said Umbo.

“I wonder which disease.”

“I don’t want to find out by catching it,” said Umbo.

“Poisoning them,” said Param. “The mice are going to murder the entire population of Earth.”

“Have you got her language?” asked Umbo.

“Yes,” said Param.

“You go to them invisible, then appear and warn them,” said Umbo. “I’ll take you back in time with me the moment you show me a fist.”

“What message?” asked Param.

Umbo thought for a moment. “A warning. Something about how the mice are smart and very dangerous and they can’t let a single one reach Earth.”