The shock sent Lucky's senses reeling. Any suit of ordinary metal would have bent and smashed. Any man of ordinary mettle would have been carried senseless down to the ocean floor, there to be smashed into concussion and death.

But Lucky fought desperately. Struggling against the mighty current, he brought his left arm up to his chest to check the dials that indicated the state of the suit machinery.

He groaned. The indicators were all lifeless things, their delicate workings jarred into uselessness. Still, his oxygen supply seemed unaffected (his lungs would have told him of any drop in pressure), and his suit obviously wasn't leaking. He could only hope that its jet action was still in order

There was no use trying blindly to find his way out of the stream by main force. He almost certainly lacked the power. He would have to wait and gamble on one important thing: The stream of water lost velocity rapidly as it penetrated downward. Water against water was a high-friction action. At the rim of the jet, turbulence would grow and eat inward. A cutting stream five hundred feet across as it emerged from the creature's blowpipe might be only fifty feet wide when it hit bottom, depending upon its original velocity and the distance to the ocean floor.

And that original velocity would have slowed, too. That did not mean that the final velocity was anything to deride. Lucky had felt its force against the ship.

It all depended on how far from the center of the water gush he was, on how near a bulls-eye the creature scored.

The longer he waited, the better his chances-provided he did not wait too long. With his metal-gloved hand on the jet controls, Lucky let himself be flung downward, trying to wait calmly, striving to guess how close to solid bottom he was, expecting each moment the one last concussion he would never feel.

And then, when he had counted ten, he flung his suit's jets open. The small, high-speed propellers on either shoulder blade ground in harsh vibration as they threw out water at right angles to the main current. Lucky could feel his body take on a new direction of fall.

If he was dead center, it wouldn't help. The energy he could pump up would not suffice to overcome the mighty surge downward. If he was well off center, however, his velocity would, by now, have slowed considerably and the growing zone of turbulence might not be far off.

And as he thought that, he felt his body bob and yank with nauseating violence, and he knew he was safe.

He kept "his own jets in operation, turning their force downward now and, as he did so, he turned his finger light in the direction of the ocean floor. He was just in time to see the ooze, some fifty feet below, explode and obscure everything with its muck.

He had made his way out of the stream with but seconds to spare.

He was hurrying upward now, as fast as the jet motors of his suit would carry him. He was in desperate haste. In the darkness within his helmet (darkness within darkness within darkness) his lips were pressed into a narrow line and his eyebrows pulled down low.

He was doing his best not to think. He had thought enough in those few seconds in the water spout. He had underestimated the enemy. He had assumed it was the gigantic patch that was aiming at him, and it wasn't. It was the V-frogs on the water's surface that controlled the patch's body through its mind! The V-frogs had aimed. They did not have to follow the patch's sensations in order to know it had been hit. They needed only to read Lucky's mind, and they needed only to aim at the source of Lucky's thoughts.

So it was no longer a matter of pin-pricking the monster into moving away from the Hilda and lumbering down the long underwater declivity to the deeps/that had spawned it. The monster had to be killed outright.

And quickly!

If the Hilda would not take another direct blow, neither would Lucky's own suit. The indicators were gone already; the controls might go next. Or the liquid-oxygen containers might suffer damage to their tiny force-field generators.

Up and still up went Lucky, up to the only place of safety. Although he had never seen the monster's blowpipe, it stood to reason that it must be an extensible and flexible tube that could point this way and that. But the monster could scarcely point it at its own undersurface. For one thing, it would do itself damage. For another, the force of the water it expelled would prevent that blowpipe from bending at so great an angle.

Lucky had to move up then, close to the animal's undersurface, to where its weapon of water could not reach; and he had to do it before the monster could fill its water sac for another blow.

Lucky flashed his light upward. He was reluctant to do so, feeling instinctively that the light would make him an easy target. His mind told him his instinct was wrong. The sense that was responsible for the monster's rapid response to his attack was not sight.

Fifty feet or less above, the light ended on a rough, grayish surface, streaked with deep corrugations. Lucky scarcely attempted to brake his rush. The monster's skin was rubbery and his own suit hard. Even as he thought that, he collided, pressing upward and feeling the alien flesh give.

For a long moment, Lucky drew deep gasps of relief. For the first time since leaving the ship, he felt moderately safe. The relaxation did not last, however. At any time the creature could turn its attack (or the small mind-master that controlled it could) on the ship. That must not be allowed to happen.

Lucky played his finger flash about his surroundings with a mixture of wonder and nausea.

Here and there in the undersurface of the monster were holes some six feet across into which, as Lucky could see by the flow of bubbles and solid particles, water was rushing. At greater intervals were slits, which opened occasionally into ten-foot-long fissures that emitted frothing gushes of water.

Apparently this was the way the monster fed. It poured digestive juices into the portion of the ocean trapped beneath its bulk, then sucked in water by the cubic yard to extract the nutriment it contained, and still later expelled water, debris, and its own wastes.

Obviously, it could not stay too long over any one spot of the ocean or the accumulation of its own waste products would make its environment unhealthy. Of its own account it would not have lingered here so long, but with the V-frogs driving it...

Lucky moved jerkily through no action of his own and, in surprise, turned the beam of light on a spot closer to himself. In a moment of stricken horror, he realized the purposes of those deep corrugations he had noticed in the monster's undersurface. One such was forming directly to one side of him and was sucking inward, into the creature's substance. The two sides of the corrugation rubbed against one another, and the whole was obviously a grinding mechanism whereby the monster broke up and shredded particles of food too large to be handled directly by its intake pores.

Lucky did not wait. He could not risk his battered suit against the fantastic strength of the monster's muscles. The walls of his suit might hold, but portions of the delicate working mechanisms might not.

He swung his shoulder so as to turn the suit's jets directly against the flesh of the monster and gave them full energy. He came loose with a sharp smacking sound, then veered round and back.

He did not touch the skin again, but hovered near it and traveled along it, following the direction against gravity, mounting upward, away from the outer edges of the thing, toward its center.

He came suddenly to a point where the creature's undersurface turned down again in a wall of flesh that extended as far as his light would reach on either side. That wall quivered and was obviously composed of thinner tissue.

It was the blowpipe.

Lucky was sure that was what it was-a gigantic cavern a hundred yards across, out of which the fury of rushing water emerged. Cautiously Lucky circled it. Undoubtedly this was the safest place one could be, here at the very base of the blowpipe, and yet he picked his way gingerly.

He knew what' he was looking for, however, and he left the blowpipe. He moved away in the direction in which the monster's flesh mounted still higher, until he was at the peak of the inverted bowl, and there it was!

At first, Lucky was aware only of a long-drawn-out rumble, almost too deep to hear. In fact, it was vibration that attracted his attention, rather than any sound. Then he spied the swelling in the monster's flesh. It writhed and beat; a huge mass, hanging thirty feet downward and perhaps as big around as the blowpipe.

That must be the center of the organism; its heart, or whatever passed for its heart, must be there. That heart must beat in powerful strokes, and Lucky felt dizzy as he tried to picture it. Those heartbeats must last five minutes at a time, during which thousands of cubic yards of blood (or whatever the creature used) must be forced through blood vessels large enough to hold the Hilda. That heartbeat must suffice to drive the blood a mile and back.

What a mechanism it must be, thought Lucky. If one could only capture such a thing alive and study its physiology!

Somewhere in that swelling must also be what brain the monster might have. Brain? Perhaps what passed for its brain was only a small clot of nerve cells without which the monster could live quite well.

Perhaps! But it couldn't live without its heart. The heart had completed one beat. The central swelling had contracted to almost nothing. Now the heart was relaxing for another beat five minutes or more from now, and the swelling was expanding and dilating as blood rushed into it.

Lucky raised his weapon and with his light beam full on that giant heart, he let himself sink down. It might be best not to be too close. On the other hand, he dared not miss.

For a moment a twinge of regret swept him. From a scientific standpoint it was almost a crime to kill this mightiest of nature's creatures.

Was that one of his own thoughts or a thought imposed upon him by the V-frogs on the ocean surface?

He dared wait no longer. He squeezed the handgrip of his weapon. The wire shot out. It made contact, and Lucky's eyes were blinded by the flash of light in which the near wall of the monster's heart was burnt through.

For minutes the water boiled with the death throes of the mountain of flesh. Its entire mass convulsed in its gigantic writhings. Lucky, thrown this way and that, was helpless.

He tried to call the Hilda, but the answer consisted of erratic gasps, and it was quite obvious that the ship, too, was being flung madly about.

But death, when it comes, must finally penetrate the last ounce of even a hundred-million-ton life. Eventually a stillness came upon the water.

And Lucky moved downward slowly, slowly, weary nearly to death.

He called the Hilda again. "It's dead," he said. "Send out the directional pulse and let me follow it down."

Lucky let Bigman remove his sea suit and managed a smile as the little Martian looked worriedly up at him.

"I never thought I'd see you again, Lucky," said Bigman, gulping noisily.

"If you're going to cry," said Lucky, "turn your head away. I didn't get in out of the ocean just to get all wet in here. How are the main generators coming along?"

"They'll be all right," put in Evans, "but it will still take time. The knocking around just at the end there ruined one of the welding jobs."

"Well," said Lucky, "we'll just have to get on with it." He sat down with a weary sigh. "Things didn't go quite as I expected."

"In what way?" demanded Evans.

"It was my notion," said Lucky, "to pin-prick the monster into moving off us. That didn't work, and I had to kill him. The result is that its dead body has settled down around the Hilda like a collapsed tent."