Ken's reflections brought an urge to get the present job over with as quickly as possible. He squeezed another ounce of speed from the torpoon, taxing it to the limit and setting up a slight vibration; then he fondled the nitro-shell gun's trigger and studied the huge fish bodies ahead.

"Seems as if they're going to run forever," he muttered indignantly. "We'll be to the Pole if they keep it up!"

Already the Narwhal was miles behind. Through the torp's vision-plate a scene of ever increasing mystery and gloom met his gaze. The killers' course had brought them beneath a wide sheet of ice, apparently, for there were no more columns of pale sunlight piercing through. The quarter-light monotone was unbroken, save by deeper drifts of shadow, and as he drummed through it the torpooner wondered at its lifelessness. He discerned no more of the ghostly fish-schools that usually abounded. Some enemy possibly had driven them from the region; but not the whale he was pursuing, for they scorned such fare.

He was scanning the surrounding murk apprehensively, when, of a sudden, his brain and body tensed.

Off to one side, far to the right, he thought he had glimpsed a figure. It was hanging motionless, level with him; and at first it looked like a seal. But the flippers seemed longer than a seal's; moreover, no seal would be anywhere near a pack of killer whales; nor did they poise in an upright position. It couldn't be a seal, he told himself. What, then? Was it only imagination that made it appear faintly human-shaped?

He strove to catch it again with staring eyes, but it was gone, leaving only a jumbled impression of something fantastic in his mind, and the next instant the whole thing was forgotten in the movements of the killer school, now only a few hundred yards ahead.

They suddenly began a great sweeping curve to the right, a typical maneuver before standing for attack or breaking up. At once Ken swerved to starboard and drove the torpoon's nose for an advance point on the circle the fish were describing. His move swallowed the distance between them; the sleek, thick-blubbered bodies swept close by his vision-plate, their rush tossing the torp slightly. Twelve of them went past in a blur, and then came the thirteenth, the invariable straggler of a school. The thin light-beams pencilled through the darkness, outlining the rushing black shape; Ken gripped the gun's trigger and jockeyed the torp up a trifle in the seconds remaining, always keeping the sights dead set on the vital spot twelve inches behind the whale's little eye.

When only fifteen feet separated them he squeezed the trigger and at once zoomed up and away to get clear of the killer's start of pain and, if the shot were true, its following death flurry.

The shell slid deep into the rich outer blubber; and, wheeling, Ken watched the mighty mammal quiver in its forward rush. This was merely the reaction from the pain of the shell's entrance; the nitro had not as yet exploded.

Now it did. The projectiles carried but a small charge, in order not to rip too much the buoyant lungs and so cause the body to sink, but the killer trembled like a jelly from the shock. The heart was reached; its razor-sharp flukes thrashing and tooth-lined jaws clicking, the killer wheeled with incredible speed in its death flurry. A minute later the body shuddered a last time, then drifted slowly over, showing the white belly. It began a gentle rise up toward the ceiling of ice.

"One!" grinned Ken Torrance. He noted his position on the torpoon's dials and gave it to the Narwhal by radio. They would then follow and pick up the whale.

"I'll have the second in ten minutes," he promised confidently. "Signing off!"

Again the torp darted after its prey.

He found it easy, this time, to overhaul them. Not many minutes had elapsed before he again caught sight of their rhythmically thrusting flukes and the flash of white under-sides. Unaware that one of their fellows had been left a lifeless carcass by the steel fish again nearing them, they had reduced their speed somewhat.

Ken angled down a hundred feet into the deeper shadows, not wanting to apprise them of his presence. He continued at that level until the belly of the rearmost whale rolled white above him; then he veered off to the left, rising as he did so, in order to bring his assault to bear directly on the killer's flanks.

He swung back and streaked in for the kill. It looked like an easy one.

But he was never more mistaken in his life. For, as luck had it, he had chosen a tartar, a fighting fish—literally the "killer" which its kind had been named.

The torpooner knew what he was in for as soon as he fired his first shell. Its aim was bad, and instead of sinking into the flesh it merely ripped across the whale's back, leaving a ragged, ugly scar.

An ordinary whale would have been scared into panic by the wound and doubled its speed in an effort to get away; but Ken Torrance saw this one wheel its six-foot snout around viciously until its beady little eyes settled on the torpoon.

"I'll be damned!" he muttered. "He's turning to fight. All right, come ahead!"

He veered about and fired another shot that missed its mark by feet, but creased the whale's flukes. At once this terrible weapon lashed titanically up and down, and thirty feet of berserk killer came curving towards the lone man inside his shell of steel. Ken tensed himself for combat. He would have to keep a good distance from the fish and fire until he got it, as a square smash from its flukes might crumple the torp like an egg-shell.

Thirty feet of berserk killer came curving towards the lone man.

But his foe gave him no chance. Crazy with pain and anger, it swept up and nipped his dive for the bottom with a fluke-blow that tumbled the torpoon over and dazed its pilot. Before he could get straightened out it was on him again, catching him up into a wild whirlpool, butting the shell and flashing round to get its flukes into position. With a wrench, Ken jammed the rudder over, shoved his accelerator flat, and got free just as the tail thrashed down. He was breathing hard and sweating as he banked around—to see once more the whale, its wicked jaws wide open, charging directly at him.

For a moment he was unable to move. Such a mode of attack was totally unexpected, and the sight held him fascinated. He could see the very wrinkles of the monster's skin as it rushed in, with shadowy flukes thrusting behind; could see the lines of dagger-like teeth, the cavernous maw and gullet. And then all vision was blotted out as the jaws closed around the torpoon's nose.

Ken did not wait for those jaws to crunch shut. He gripped the nitro-shell gun's trigger and squeezed it back.

The weapon hissed, flung its shell. He reversed his engines to try and tear free. Seconds dragged by with no result. Then he felt a mighty jolt; his harness broke; and he was pitched into the torp's engine controls.

That was all he knew, save for a vague feeling of falling, falling over and over, which was ended when a second bone-shaking shock brought complete oblivion....

It was darkness that met his eyes when they opened, the eery darkness of the floor of the Polar Sea.

Darkness! Half-conscious as he was, he started in surprise. He looked for the torp's shaded control board-lights, but could not find them. Bewildered, he wondered what had happened, and then remembered the whale. In its flurry it had smashed him down.

Pain was thumping his forehead where he had struck the control levers; with a groan he twisted his body around and felt for his hand-flash. At any rate, there was no water inside the body compartment. The seams had resisted the blow. But why were