"I don't think there's much danger. They won't be roaming around in that storm outside."
The boys resumed their search of the cave. They turned the flashlight high and low in the hope of finding the tunnel that had been so plainly marked on the plan, but without success.
"We must have taken the wrong passage," Joe remarked.
"I'm positive we took the right one. I took special care—But say! Perhaps the tunnel has been covered up!"
"That's an idea. It may be hidden."
Frank turned the light on the heap of rocks and gravel in one corner of the cave. At the base of the pile he could see footprints, all of which led directly to or from the heap.
"Maybe this is where it is," he said, and, handing Joe the flashlight, he picked up the shovel. He attacked the gravel vigorously, casting shovelfuls of it to one side. In a few moments he gave an exclamation of satisfaction. For, back of the gravel he had shoveled away, he saw a wooden door.
"Now we're getting there!"
The gravel flew, and in a short time the door was revealed, back of a heap of boulders that the boys lost no time in rolling to one side. To their disappointment they found a rusty padlock on the door, but Joe remembered the broken pickax they had seen in the chamber a short while before and he seized it. A few sharp blows and the padlock lay broken and shattered. He wrenched at the door and it came slowly open, with a protesting creak of hinges.
Casting the shovel to one side, Frank once more took the lead and they passed through the doorway. The tunnel at this point was very rough and narrow. They made their way cautiously forward. Frank noticed a change in the color of the earth and rock at this juncture.