They passed the dark mouths of unlit tunnels branching ahead from this illuminated one. Then over the booming of the raging sea above them, there came to Ennis' ears the distant, swelling chant they had heard in the water-cavern above. But now it was louder, nearer. At the sound of it, Chandra Dass quickened their pace. Suddenly Inspector Campbell stumbled on the slippery rock floor and went down in a heap. Instantly Chandra Dass and his two followers recoiled from them, the two pistols trained on the detective as he scrambled up. "Do not do that again, inspector," warned the Hindoo in a deadly voice. "All tricks are useless now." "I couldn't help slipping on this wet floor," complained Inspector Campbell. "The next time you make a wrong step of any kind, a bullet will smash your spine," Chandra Dass told him. "Quick--march!" * * * * * The tunnel turned sharply, turned again. As they rounded the turns, Ennis saw with a sudden electric thrill of hope that Campbell held clutched in his hand, concealed by his sleeve, the heel-hilted knife from his shoe. He had drawn it when he stumbled. Campbell edged a little closer to the young American as they were hastening onward, and whispered to him, a word at a time. "Be--ready--to jump--them----" "But they'll shoot, your first move----" whispered Ennis agonizedly. Campbell did not answer. But Ennis sensed the detective's body tautening. They came to another turn, the strong, swelling chant coming loud from ahead. They started around that turn. Then Inspector Campbell acted. He whirled as though on a pivot, the heel-knife flashing toward the men behind them. Shots coughed from the pistols that were pressed almost against his stomach. His body jerked as the bullets struck it, yet he remained erect, his knife stabbing with lightning rapidity. One of the hooded men slumped down with a pierced throat, and as Campbell sprang at the other, Ennis desperately launched himself at Chandra Dass. He bore the Hindoo from his feet, but it was as though he was fighting a demon. Inside his gray robe, Chandra Dass writhed with fiendish strength. Ennis could not hold him, the Hindoo's body seeming of spring-steel. He rolled over, dashed the young American to the floor, and leaped up, his dark face and great black eyes blazing. Then, half-way erect, he suddenly crumpled, the fire in his eyes dulling, a call for help smothered on his lips. He fell on his face, and Ennis saw that the heel-knife was stuck in his back. Inspector Campbell jerked it out, and put it back into his shoe. And now Ennis, staggering up, saw that Campbell had knifed the two hooded guards and that they lay in a dead heap. "Campbell!" cried the American, gripping the detective's arm. "They've wounded you--I saw them shoot you."