The explosion was a great disappointment.
He could hardly tell when it happened. There was no great spout of white foam, no thundering crash. There were not even bubbles. There was only a small upthrust of gentle, slow water in the middle of the lake, like some great fish disporting itself just below the surface. A distant, mild rumble. Nothing else.
Tupaia swore angrily. No matter! It was time to make his move. He started to spin, to run toward the trees—
And froze. With a snare-drum rattle of fury the Scorpian robot was jetting directly toward him, followed by the Watcher and the Sirian eye . . . and how had they known?
But they hadn't known what he was doing. They were not after Tupaia at all. They overflew him, dived into the woods, and disappeared. There were sounds of a scuffle, and then they came back, in line of procession, with the Sirian robot in the middle, clutching, in one disdainful tentacle, the queerly dressed chimpanzee.
As they passed, the Sirian eye sent a casual stinging electric lash in Tupaia's direction, warning him back toward the shore. He had no choice. He obeyed; and as he turned back he heard a sad, whimpering voice: "Oh, please! I wasn't doing any harm! I was just on a, uh, a scientific expedition—"
It was the chimp! And he was speaking English!
Te'ehala Tupaia could not help himself; he expanded his barrel chest and roared with laughter. The chimp, carried like a rag doll in the robot's contemptuous grasp, wriggled around far enough to stare down at him reproachfully. Now he was upside down, whimpering with fear, a bedraggled monkey in yellow shorts and bright red jacket. Even though it had cost Tupaia his best chance at freedom, it was funny!
And then the humor ended. He heard a strange sound from the lake, and when he looked he saw that it was quietly emptying itself.
When the bomb blew out the underwater door, it had not been to connect with some still deeper, vaster body of underground water. It had been like blowing the stopper out of a tub. There was a slow, chuckling gurgle from the middle of the lake, as its whole surface began to stir, and circle, and narrow down to a gentle whirlpool at the center. Already the edge of the water had retreated a dozen meters from the beached raft as the lake, with all deliberate speed, drained itself into the empty caverns below.
Two days later the comedy was not even a memory. There was no longer anything for Te'ehala Tupaia to laugh at. Escape had failed. Every hour they were deeper and deeper into the shell of Cuckoo, and the hours were many.
What drove the aliens to this headlong plunge into the depths Tupaia did not know, but the aliens remorselessly drove him, and the rest of the Purchased People with him. They were beasts of burden. Once past the blown-out gate at the end of the porcelain road they were in a narrow, dark tunnel that spiraled down and down. The Sirian eye produced headlamps from one of the containers of instruments, tools, and weapons—eight of them for the Earth- primate labor squad, or about one for every other slave. The Scorpian had built-in lights of his own; the Sirian lit his way with coronal discharges of electricity when he needed them, and the other aliens had lamps given to them as a matter of course. Tupaia had one, of course. If he had not, he would have taken it from the nearest other; it was obvious that it was better to have it than not, if one must be a beast of burden at all.
And beast of burden he was, for what he had been made to carry was the great translucent block with the keyboard. Was it really a weapon? He was convinced it was, for the slave drivers kept a special eye on him, the Watcher's reek never out of his nostrils as the hideous creature soared overhead, except when the Sirian eye or the Scorpian was there. The thing outweighed Tupaia's own hundred-kilos- plus; on Earth he could barely have lifted it, and he was glad when the aliens commanded other Purchased People to take it in turn.
And they traveled down and down . . .
It was clear, at least, that this was no natural cave; the walls were metal, regular, with queer niches and protuberances that must once have had some function. It was an artifact. And it was immense! It seemed endless, and so steep that even in Cockoo's forgiving gravity it was hard to traverse.
Worse, it was slippery. The cascade from the lake had gone before them. It had kept on going, to depths unguessable to Tupaia; but in its passage it had left a coating of slimy muck. Even for Tupaia's huge strength, guiding the great massy block along the unpredictable jogs and bends of the tunnel was hazardous. At one switchback, damp and oily, the young blond girl slipped and fell headlong. Tupaia, trying to avoid her, stumbled himself, and would have fallen except that a long, skinny black arm snaked out of nowhere and caught him.
"Watch it, big fellow," chattered an unhappy voice.
It was the ape, staggering under a load almost as great as Tupaia's own. Tupaia stopped his block and turned to see him with the headlamp, scowling. The poor creature ducked his head, half-blinded. He was only an animal—
But a king-warrior did not fail to acknowledge a favor. "Here," he said gruffly, "let me help you with that."
The chimp sighed, shifting the burden. "Well, thanks," he said, "but I'm a lot stronger than I look. But if you want to do something for me—"
Tupaia frowned. "What?" he demanded.
"Well, if you'd just shine that light straight ahead for a minute. —That's right. Thanks! And now at the walls of the tunnel, and then at the stuff I'm carrying—"
Tupaia caught himself automatically doing as the chimpanzee had asked, and stopped. "What's this about?" he asked suspiciously.
The chimp grimaced with fear. "Please, not so loud! It's just that I have this tachyon camera. See, this little thing, strapped to my wrist? I didn't lose it when they caught me—didn't even drop it, although—oh, believe me—I was so scared! I thought that minute up by the lake was going to be the last this old monkey would ever see!"
"What is it for?" Tupaia demanded, picking up his load once more.
"The camera?" The chimpanzee bared his fangs in a placatory grin. "For my friends, you see. They sent me down to keep an eye on this, and I'm doing it. Not that it matters to me, I suppose," he added, in self-pity, "because the deeper we get the surer I am that this is a one-way trip for old Doc Chimp. But at least they can see what I see— watch it!"
The procession of bearers had suddenly knotted up, because at the head of the group the aliens were squabbling over something again. Rataplan from the Scorpian robot, chitterings and yowls from the others. The ape said apprehensively, "The one that worries me is the Watcher. The others are just mean. I think he's crazy! I mean, really insane. There's something religious about this whole thing for him—he's looking for his God, sort of—and he's not finding him, and he's not sure he should have these others with him. Oh, there's going to be trouble, I promise you," he finished sorrowfully.
Carefully, Tupaia set down his ponderous burden again.
"You seem to know more about this than I do," he said slowly. "What's it all about?"
The ape sighed. "It's a long story—"
Tupaia laughed shortly. "We've got plenty of time. Maybe nothing else but time."
Down, down. Now and then they stopped to catch a few moments' sleep while the aliens wrangled. At long intervals they ate, more of the queer-tasting, metallic, faintly spoiled stuff—in Tupaia's judgment—all-purpose synthetic food from the tachyon chamber. But it kept them alive.
Escape seemed further away than ever. It was not that Tupaia was lost. Not the descendant of those Pacific explorers! But how could he get away? Always one of the flying aliens brought up the rear of the column, always the others paused even in their interminable squabbling to watch and count the slaves. It was an endless trip, with nothing to do but listen to the ape's whining complaints and ponder the meaning of what he had said. Tupaia could form no opinion of how true most of Doc Chimp's stories were. These outlandish aliens were incomprehensible in any terms; Tupaia could make no sense of the chimp's guesses at their drives and alliances. But he was surely right about the Watcher. That particular creature was growing more agitated and more frenzied at every meter. It carried no light of its own and needed none—when its bulging multiple eyes could not collect enough light to serve, its hideous black ears guided it by sonar like a bat's—and that made it all the worse. They could not see it coming as it swept back and forth over the ragged slave procession, squealing mournfully and furiously to itself by turns. The chimp's diagnosis was not to be doubted. The Watcher was mad. And when the line of porters knotted up at a dip in the tunnel where the cascading lake waters had accumulated and left a stagnant pool of thin mud, the Watcher displayed its madness. It came screeching back and struck out at the first in line, the young long-haired blond woman. Tupaia was just behind her. He dropped his burden—fortunately not the block this time!—and turned to face the attack; and something from behind struck him down. His muscles convulsed in a quick tetanic shock. He smelled ozone and his own burning flesh, and lost consciousness.