"It seems blue," he remarked to his brother. Some chemical constituent gave the underground passage that peculiar shade, discernible even in the dim light.
The tunnel narrowed and the boys squeezed their way through the passage, stepping directly into another chamber dug out of the earth. Here the blueness of the walls was intensified, the wet blue earth giving off a weird glow.
"No mistake about it this time!" declared Frank triumphantly. "We're in the blue room at last."
His words echoed and re-echoed in the confined space. The boys were trembling with excitement. The end of their search was at hand. Somewhere in that underground room lay the four bags of gold.
But where?
The floor of the chamber was unbroken. A few faint footprints could be seen, but there was nothing to indicate a secret hiding place. Frank again produced the map.
"Gold at circle," he said, reading from the instructions. "The map shows the circle to be in the far right hand corner." He went forward to the corner indicated. The earth here seemed unusually smooth and flat.
"I think it's buried here," declared Frank. "There's the mark of a shovel."
"I'll get that shovel we had in the other room. Lend me the light for a second."
Frank handed his brother the flashlight, and Joe disappeared from the blue chamber. His footsteps echoed in the narrow passage.