"Ugh!" came warningly from Red Wolf, for right before him was the cleft in the rock. No guard was there to hinder them, but they pushed forward with all caution. Tetzcatl could not be many paces farther on. He must, as yet, be entirely unaware that he had been so closely followed. "It's a hole into a den," muttered Bowie. "We've got to all but go on all-fours." It was an exciting moment with so much mystery and uncertainty just ahead of him, but he did not betray any excitement. Hardly as much could be said for the Red Wolf, for he was on an entirely new kind of hunt and it did excite him. There is a singular muscular power that often comes with the delirium of fever. It sometimes even exceeds, for a moment, the utmost strength of health. Not at all feeble, but firm and elastic, was the step with which Tetzcatl walked out from the entrance burrow into the great hall of the cavern. He went forward without a pause at first, and without speaking, although something more than ordinary was going on. The sculptured head of the war-god stood out in full relief from the dark face of the rock, for a great glare fell upon it from the altar. The fire was blazing high, revealing here and there the ghastly, ghostly figures of the priestly worshippers. They seemed to be more in number than on the day of his departure, but there were also other human beings present. Several of these latter stood immediately in front of the altar with rope fetters on their wrists. A species of monotonous chant was sounding, by discordant voices, in the tongue of the ancient race. Every now and then, as the weird, hoarse cadences rose and fell, a club was lifted, a heavy blow was struck, followed by a flash of steel and the fall of one of the fettered persons. Each shriek of fear or agony seemed to act as a signal for louder chanting, that had in it a sound of angry mockery. "God in heaven!" exclaimed Bowie, in a hushed whisper, at the upper end of the cave. "I've heard of it! I've read of it! That's an idol. They are offering human sacrifices. It's awful, and I can't do one thing for 'em. There went the last of 'em, as far as I can see. Red Wolf, keep close by me. I'm going to see this thing clean through. There goes Tetzcatl." "Ugh!" was all the reply of Red Wolf, but he was apparently quite ready to charge forward, lance in hand, if such were his orders from his white chief.