“Guess we don’t go any farther,” said Bob, dryly.

“Maybe the key’s here somewhere,” Laurie suggested; and, although Bob scoffed at the suggestion, they searched thoroughly but without success.

“We could bust it,” Bob said; “only maybe we haven’t any right to.”

“I don’t see why not, Bob. We discovered it. Let’s!”

“We-ell, but one of us’ll have to go for a hammer or something.”

“Sure; I’ll go.”

“And leave me here in the dark? I guess not!”

“We’ll both go, then. Hold on! What’s the matter with the crowbar?”

“Of course! I never thought of that! I’ll fetch it!” The light receded down the tunnel until it was small and dim, and Laurie, left alone in front of the mysterious portal, felt none too happy. Of course there was nothing to be afraid of, but he was awfully glad when the light drew nearer again and Bob returned. “You hold this,” directed Bob, “and I’ll give it a couple of whacks.”

Laurie took the lantern, and Bob brought the bar down smartly on the lock. Probably it was old and rusty, for it broke into pieces under the blow, and in another instant they had thrust the heavy bolt back. Then Bob took a long breath and pulled the door toward them. The hinges squeaked loudly, startlingly, in the silence. Before them lay darkness, and Laurie, leaning past the doorway, raised the lantern high.