aid. She, however, had been braver.

"Something is going to happen," said Tom Swift. "I feel it in my bones!"

"Bless my porous plaster!" cried Mr. Damon. "I hope it isn't anything
serious."

"We'll see," Tom went on.

They resumed their journey up the mountain trail. It wound in and out
in a region none of them had before visited. Though it could not be
far from the tunnel, it was almost a strange country to Tom.

Suddenly Masni stopped in a narrow gorge where the walls of rock rose
high on either hand. She seemed looking for something. Her sharp, black
eyes scanned the cliff and then with an exclamation of satisfaction she
approached a certain place. With a quick motion she pulled aside a mass
of tangled vines, and disclosed a path leading down through a V shaped
crack in the cliff.

"Mans down there," she said. "You go look."

For a moment Tom hesitated. Was this a trap? If he and his friends
entered this narrow and dark opening might not the Indian woman roll
down some rock back of them, cutting off forever the way of escape?

Tom turned and looked at Masni. Then he was ashamed of his suspicion,
for the honest black face, smiling at him, showed no trace of guile.

"You go--you see lost men," the woman urged.

"Come on!" cried Tom. "I believe we're on the track of the mystery!"

He led the way, followed by Mr. Damon, while Koku came next and then
Masni. It could be no trap since she entered it herself.

The path widened, but not much. There was only room for one to walk at
a time. The trail twisted and turned, and Tom was wondering how far it
led, when, from behind him, came the cry of the woman:

"Watch now--no fall down."

Tom halted around a sharp turn, and stood transfixed at the sight which
met his gaze. He found himself looking out through a crack in the face
of a sheer stone cliff that went straight down for a hundred feet or
more to a green-carpeted valley.

Tom was standing in a narrow cleft of rock--the same rock through which
they had made their way. And at the foot of the cliff was a little
encampment of Indians. There were a dozen huts, and wandering about
them, or sitting in the shade, were a score or more of Indians.

"There men from tunnel," said Masni, and, as he looked, wondering, Tom
saw some of the workers he knew. One especially, was a laborer who
walked with a peculiar limp.

"The missing men!" gasped the young inventor.

"Bless my almanac!" cried Mr. Damon. "Where?"

"He