"What's the matter?" cried Andy. "Something is happening. What is it?"
Before Frank could answer, had he known what was taking place, there came a loud splash in the water at Andy's left.
"Is that you Frank? Have you fallen?" he called desperately.
"No, I'm here," replied his brother. "That must have been part of the side or roof of the cave jarred off by the thunder. Hold fast, Andy."
There came a second splashing sound in the water, followed by another. The drops of dampness and particles of earth continued to rain into the faces of the lads.
"The cave's crumbling in!" cried Andy. "The roof is falling."
"Hold—" began Frank.
A roar interrupted him. Suddenly the cave seemed to be illuminated by a dazzling light bluish in color. By it the boys could see each other as they clung to the wall. They could see the black and swirling waters now waist high. But they could see something else.
They could look up and out through a jagged hole in the roof of the cavern, and through that opening they had a glimpse of the fury of the storm. They could see the lightning flashing in the sky.
For a moment the meaning of it was lost on them. Then Frank uttered a cry of hope.