A terrific blow struck the stern of the torpoon and spun it around dizzily. Ken made out the killer lifting its flukes for a second blow. Quickly he sped the torp ahead, and turned as best he could. Flashing on his powerful bow-beam, he found the killer to his left, slightly above. Carefully he maneuvered into firing position: then coldly, with deadly accuracy, he centered the sights of his nitro-shell gun on the vital spot behind the eyes. He pressed the trigger: again, and yet again. The projectiles hurtled out. The monster started; its beady eyes settled on the torpoon; with a lunge it darted forward, jaws gaping wide. And as it came another shell sped true into the tooth-rimmed mouth. It halted then, and doubled in the water. Shock after shock shook the torpoon as the shells exploded in the whale. For a little while the sea-beast flurried, and once or twice the torp shivered from chance fluke-blows. But then at last came peace. The body rolled over, showing its white belly, and drifted towards the trap's ceiling.... The brown-skinned heads had disappeared from the inner entrance. Kenneth Torrance glanced in that direction for a last time, then looked sadly around. "So long, Chan," he murmured. "So long." The torpoon squeezed through the bars of the outer entrance and sped forth into the open sea. * * * * * So it was that, perhaps an hour later, the light-beams of the whaling submarine _Narwhal_, doggedly scouring the region where last her first torpooner had been heard from, fell across a slim shape of steel that was beating its way at full speed through the foggy murk of the Arctic sea. Right up to the _Narwhal_ she came, swerving at the last moment and hovering outside the starboard torpoon catapult; while, aboard the submarine, an officer whose voice quivered with excitement roused Captain Henry Streight from his bunk, and the men off duty gathered around the inner catapult entrance-port. Quickly the outer port swung open. And the lone torpoon slid in--slid home.