“I hear another sound, though. It’s behind us, toward the mouth of the cave. Boys, it’s those fellows coming back. Out with that light, Paul. We’ll hide in here and surprise them. Quick! Down behind some of these boxes!”
Paul extinguished the lantern, and he and his companions sought places of concealment. They could now plainly hear footsteps approaching, while they also distinguished the murmur of excited voices.
Meanwhile, another part of the strange mystery was being enacted with the girls as principal characters. They had entered farther into the secret passage, beyond the queer swinging door which had closed after them.
“We’re caught!” cried Belle. “Oh, Cora!”
“Perhaps not,” said Jack’s sister. “If that door opened once for us it will do it again. But don’t go back. Come on. We must see what is ahead of us. The boys will laugh if they hear we turned back when we had such a good opportunity.”
“Well, they shan’t laugh at me!” declared Hazel. “I’m with you, Cora.”
“And you may be sure we’re not going to be left alone,” cried Bess. “Come on, Belle!”
The latter hesitated a moment, looked back at the closed door, and then went forward. Their lamps made the place fairly light, and they could see that the passage was planked here as it had been nearer the bungalow.
They had gone on perhaps fifty paces more and were wondering when the queer tunnel would come to an end, when Cora, who was walking in advance with Hazel, put her hand on her companion’s arm, and cried:
“Do you hear it?”