The sledges crawled along. The invaders seemed too busy trying to blast the research base off the face of Gilver to bother doing anything about them. Jennifer wondered if that was too good to last. A moment later, she wished she hadn't, because it was. Something cracked past her ear. Then another something smacked off the rear facing of the sledge, hard enough to make it shudder under her. It kept running, though.

She turned around again. A couple of big aliens were bounding after her and Greenberg. As she'd feared, they ran faster than the sledges. Nothing grew in the area of the Great Unknown. There was no place to hide, save possibly behind the massive columns of the colonnade. The only weapon she had was her stunner, which might make a Foitan scratch but assuredly would not stop him. In any case, the soldiers' hand weapons far outranged the feeble thing.

Greenberg had seen the Foitani, too. If he felt the same choking despair that cast its pall over her, he did not show it. In fact, he stood up on his sledge?it was slow enough and smooth enough to make that safe?and jumped up and down thumbing his nose at them. That only made them run harder?and all at once, Jennifer realized he wanted exactly that. "You're a genius, Bernard!" she shouted. She stood up on her sledge, too.

The Foitani from Rof Golan kept coming. All too soon, they were only a couple of hundred meters behind the sledges. The closer they drew, the more easily Jennifer could see they were not the same as Foitani from Odern. They were taller and leaner and nearer gray than blue. Their ears were larger. So were their muzzles?and their teeth. They had red marbles for eyes, not black ones. That made them seem all the fiercer as they bore down on the humans.

Their clawed feet slapped on the smooth stone of the pro-cessionway. Jennifer heard their harsh breathing closer, ever closer. She reached into her beltpouch for her stunner, though she knew a steak knife would have done more good. She put away the stunner. If these Foitani had decided to take them prisoner instead of slaying them out of hand, she would not try to change their minds.

The Foitani caught up with the sledges. They even smelled different from the Foitani of Odern?sharper, like ripe cheese, Jennifer thought as she waited to be seized. The Rof Golani Foitani ran past her and Greenberg, on either side of their sledges. They paid no attention whatever to the humans. Their red eyes were only on the tower ahead. Like two big machines, they pounded toward it.

Jennifer watched their backs recede ahead. "I think we may take it as proved that the Great Unknown affects more than one type of Foitani descendant," she said. She was proud of herself. The sentence came out as cleanly as if she were dictating an academic paper into the Middle English Scholars Association data net.

Greenberg gave her an odd look. "Yes, I think we may," he answered, half a beat late. "I think it's a good thing, too."

"So do I." Jennifer steered her sledge up next to his. She reached across and took his hand. Her own palm was cold and trembling. The vibration of the two sledges didn't let her tell if he also had the shakes, but he felt no warmer. After a moment, she added, "That was good thinking, luring them on into the zone of insanity. Now all they care about is the Great Unknown. Right now, they can keep it, as far as I'm concerned. I don't think I was made to be a soldier."

"Neither was I," Greenberg said. "I kept thinking about getting behind you and setting off Enfram Enfram Marf's shaped charge at the Foitani. By the time I decided it wasn't a good idea, they'd already gone by us."

"You still did better than I did," she said. "I forgot all about the stupid thing."

"That's not so good, Jennifer," he said seriously. "You should never forget about anything."

The sledges ground on toward the central tower. Jennifer kept looking back at the research base of the Foitani from Odern. The one good thing about the fighting that continued all around it was that the Foitani from Rof Golan weren't using nuclear weapons, as they had when they attacked from space. Maybe now, she thought, they were more interested in conquest than in annihilation. She hoped they would go on thinking that way; she had no confidence in the Great Unknown's ability to keep fallout from the local atmosphere.

Several other Foitani from Rof Golan strode the procession-way behind the first two. None passed the sledges, which by then were more than halfway from the outer edge of the radius of doom to the central tower. None shot at the sledges, either, for which Jennifer was duly grateful. A couple of kilometers from the tower, the sledges, slow but mechanically steady, repassed the first two Foitani soldiers. Their gray-blue fur was damp with sweat; their tongues lolled from their mouths. They did not glance at the machines or the humans aboard them, but kept trudging toward the tower at the best speed they could muster.

The tower grew closer and closer. The two sledges stopped a couple of meters away. Greenberg climbed down from his sledge, lifted the shaped charge Enfram Enfram Marf had given him, and carried it to the side of the immense white structure. He pressed it against the stone. Jennifer wondered if it would stick, as it had against the practice slab of stone. The material of the Great Unknown seemed much more than simple white marble. But stick the charge did.

Greenberg went back to the sledge and called the research base. "We have the entry charge in place. Please advise if we should proceed, under the circumstances." Only static came from the speaker. Either no one at the base was listening, or the Rof Golani were jamming the channel. Greenberg looked at Jennifer. "What do you think we ought to do?"

"I think we ought to blow it," she said without hesitation. "We're never going to have a better chance than this. I just hope it's not all for nothing anyway?if the Foitani from Rof Golan win, what's going to happen to the Harold Meeker?"

"That's such a good question, I've done my best not to think about it." Greenberg made a sour face. He ran wire from the charge back to the detonator. "We have a couple of hundred meters to retreat. Let's use them." The sledges went into reverse until the wire began to grow taut.

Greenberg dismounted again and got behind his sledge. Jennifer took cover, too. She said, "I'm just glad this thing doesn't have to be set off by radio from the base, the way the practice charge did."

He let out a wry chuckle. "That would rather ruin our day's work, wouldn't it?"

"You might say so, yes," she answered, trying to match him dry for dry. She heard the slap-slap-slap of Foitani feet on the processionway. The first two soldiers from Rof Golan were getting close again. "If you're going to do it, you'd better do it now."

Greenberg glanced back toward the Foitani. He nodded. "Right you are." He brought his thumb down on the blue firing button. He grunted?squeezing the contact closed took considerable effort. Not only were Foitani stronger than people to begin with, the firing button was rigged so it could not go off by accident.

After the bombardment she'd been through, Jennifer found the detonation of the shaped charge an anticlimax. Unlike munitions makers, blasting experts do not make their devices as strong as possible, only just strong enough to do a particular job. Even in quiet circumstances, the blast would hardly have made her jump.

She looked up over the top of the sledge. Just as in the practice run, Enfram Enfram Marf's charge had blown a neat, round hole in the white stone of the tower. Blackness lay beyond it.

Greenberg looked up, too, then grabbed the communicator. "Calling the research base. I don't know whether you can see it?for that matter, I don't know if you can hear me?but we have succeeded in making a breach in the base of the column at the center of the Great Unknown."