McGrath crouched above his motionless victim, listening. There was no sound near by--but suddenly, far away, there rose a long-drawn shriek that shuddered and died away. The blood congealed in McGrath's veins. Once before he had heard that sound--in the low forest-covered hills that fringe the borders of forbidden Zambebwei; his black boys had turned the color of ashes and fallen on their faces. What it was he did not know; and the explanation offered by the shuddering natives had been too monstrous to be accepted by a rational mind. They called it the voice of the god of Zambebwei. Stung to action, McGrath rushed down the path and hurled himself against the back door of the cabin. He did not know how many blacks were inside; he did not care. He was berserk with grief and fury. The door crashed inward under the impact. He lit on his feet inside, crouching, gun leveled hip-high, lips asnarl. But only one man faced him--John De Albor, who sprang to his feet with a startled cry. The gun dropped from McGrath's fingers. Neither lead nor steel could glut his hate now. It must be with naked hands, turning back the pages of civilization to the red dawn days of the primordial. With a growl that was less like the cry of a man than the grunt of a charging lion, McGrath's fierce hands locked about the octoroon's throat. De Albor was borne backward by the hurtling impact, and the men crashed together over a camp cot, smashing it to ruins. And as they tumbled on the dirt floor, McGrath set himself to kill his enemy with his bare fingers. The octoroon was a tall man, rangy and strong. But against the berserk white man he had no chance. He was hurled about like a sack of straw, battered and smashed savagely against the floor, and the iron fingers that were crushing his throat sank deeper and deeper until his tongue protruded from his gaping blue lips and his eyes were starting from his head. With death no more than a hand's breadth from the octoroon, some measure of sanity returned to McGrath. He shook his head like a dazed bull; eased his terrible grip a trifle, and snarled: "Where is the girl? Quick, before I kill you!" De Albor retched and fought for breath, ashen-faced. "The blacks!" he gasped. "They have taken her to be the Bride of Zemba! I could not prevent them. They demand a sacrifice. I offered them you, but they said you were paralyzed and would die anyway--they were cleverer than I thought. They followed me back to the Manor from the spot where we left the Arab in the road--followed us from the Manor to the island.