The Bradys drew their pistols, got their dark lanterns ready for use, and descended the stairs for a distance of fifteen feet.

They found themselves in a big natural cavern, and as they flashed their lantern lights around in the gloom, a cry of the most intense astonishment burst from their lips.

CHAPTER XV.

THE PRISONER IN THE CAVE.

"Harry, this is the most astonishing place I ever was in in all my life."

"It certainly is wonderful, Old King Brady."

The detectives were gazing in amazement where the lights of their lanterns rested, and beheld a wonder of nature very seldom seen.

In the first place, they were in a huge cavern of circular shape.

The flight of stairs wound around one of the walls, and beside the bottom step there was a yawning hole in the ground fifty feet in diameter.

It seemed to go straight down into the earth.