"But why was it not used against us?" asked the missionary.
"It may not have been known to Wana Affghar; some of his men, no doubt the guard along the river bank, stumbled upon it, and one of them explored it to find out whether it could be used. They didn't tell their leader, or, if they did, the old wretch must have seen that it was unknown to us. As a consequence, he has simply guarded the outlet."
"I wonder that it has not been employed against us."
"I believe it would have been used tonight, but for this ransom business. Wana Affghar is such a scoundrel that I am convinced he will attack us if we leave by the regular way. Let us hunt for the underground passage."
"I agree with you," remarked Mr. Hildreth, much impressed by what was said.
"Keep watch, then, for a few minutes, while I make search for it," said Avery, hurrying away in considerable excitement.
The story of Marian Hildreth proved that the intruder of the night before came from the larger apartment into the smaller, so that the opening must be looked for in the former. There, then, the doctor began his explorations.
He first stamped upon the floor, treading upon every portion of the stone and cement, and listening for the hollow sound which tells of the excavation below.
After making a complete circuit, he thought he detected this peculiarity near one of the corners, though it was not pronounced. He struck a light and carefully scrutinized the floor, but saw nothing to explain the phenomenon.
"In whatever way he entered, he did not come up through the floor. Since the opening can't be in the roof, it must be in the wall."