Together they advanced, with Mayhew keeping them company. All were constantly on the alert for signs of treachery and danger. Those who dealt with the tricky red sons of the forest in the pioneer days learned to be always on the watch. Now the sounds ceased, and the boys exchanged looks, as if asking each other whether this could have anything to do with their arrival. Were hostile eyes watching them from some rocky covert; and would a signal be given to launch an attack? Dick, examining what lay just beyond, came to a conclusion. "There is a gaping hole yonder, you see, Roger?" he noted. "Where the rocks seem to drop straight down, you mean?" replied the other. "Yes, and it is out of that hole the sounds came. Let us stand here, and wait to see if we can hear them again." They had not long to wait. Even as they stood listening intently, there came once more a long-drawn moan, which was followed by others. Then succeeded a rattling sound as though some heavy body were endeavoring to creep up the slanting rock, only to slip back again. They even heard the thud that seemed to announce the end of the vain attempt. Still it was all unintelligible to both Dick and Roger. While the groans continued to well up out of the basin, they again started to creep forward. The brink was within plain sight, and in another minute they would be in position to peer over the edge. What new and terrifying wonder they might discover there they could not even guess, yet it was with a thrill that the lads kept on, covering the intervening rock foot by foot. They reached the brink together, and both immediately thrust out their heads to take the first look. Only for a brief space of time did they stare downward, and then, just as a cautious tortoise might draw back his head within his shell, Dick and his companion retreated. "Oh!" gasped Roger, as he turned his face, filled with perplexity, toward the other, "did you see what it was, Dick?" "After all, nothing so strange as we thought," replied the other. "Instead of a supernatural happening, it was real human groans we heard. There are men trapped in that hole, and they have tried again and again to climb up, always to slip back again. They must he battered, and nearly starved, which would be enough to make them groan, I think." "But, Dick, I saw one of them plainly, and I knew him, too!" urged Roger, bluntly. "Then you saw more than I did," the other told him. "From the fact that they are dressed in buckskin I knew they must be hunters or trappers, but supposed it would turn out that they were French voyageurs, such as have roamed throughout the Northwest country since the time of Pontiac. Who was the man you saw, Roger?"