“There’s daylight ahead,” thought the boy. “That must be where the fresh air comes from,” for he had noticed that the tunnel was not close, but that a current of air was circulating through it. Fenn was wrong as to the source of this supply, as he learned later, but he had little time to speculate on this matter, for, much sooner than he expected, he had reached the spot of the light.
He saw, suddenly looming before him, an opening that marked the end of the tunnel. The shaft gave a sharp upward turn and Fenn was shot up and out, just as are packages that are sent down those iron chutes from the sidewalk into store basements.
A moment later the boy, covered with mud from head to foot, found himself on a narrow ledge on the face of a cliff overlooking Lake Superior. He lay, partly stunned for a moment, and blinking at the strong light into which he had come from the darkness of the shaft.
Below him rolled the great lake, on which he and his chums had so recently been sailing in the Modoc. Fenn arose to his feet, and gave a glance about him.
“It’s the same place!” he murmured. “The same place where we saw the men who so mysteriously disappeared! I’m on the track of their secret!”
He looked at the ledge on which he stood. It was long and narrow, and, not far from where he was, he saw a partly-round opening, that seemed to be the mouth of another shaft, leading straight down.
“Well, more wonders!” exclaimed Fenn, walking toward it. As he did so, he was startled to see the head of a man emerge from the second shaft. The fellow gave one look at Fenn and then, with a cry of warning to some one below, he disappeared.
Fenn, startled and somewhat alarmed, hesitated. He was on the brink of an odd discovery.