At this juncture he heard voices coming from the river. They were punctuated by the dip of oars. As he heard the speakers outside, Dick's mind suddenly realized who "W. M." was.
"What a chump I was not to think of it before!" he exclaimed." It's William Masterson, of course, and that's his voice outside. Gee whillakers, they must have camped here on purpose to spy on us."
Just then it occurred to Dick that he was, as a matter of fact, spying on Masterson. He went to the cave door. Below was a boat containing Masterson and his two friends. They had apparently been to town for supplies, for the boat was full of canned goods and provisions.
Just as Dick got to the door Masterson spied the home-made boat lying on the bank at the foot of the cliff.
"Say, fellows," he exclaimed, "somebody's been paying us a call."
"Some thieving Indian, judging from the looks of that boat," said Sam Higgins.
"Well, we're not receiving callers of any kind right now," sputtered Eph angrily.
Dick crouched back into the doorway of the cave. He was trying to think what to do. It was an awkward situation. He didn't want to be caught in what looked, on the face of it, like an act of spying, and yet he didn't wish Masterson and his cronies to think him a coward.
"Say, fellows," spoke up Higgins suddenly, "you don't think it could be one of those kids from the camp below, do you? They may have seen us snooping around there at night and got wise to where we are hiding."
"It had better not be one of them," said Masterson in a loud, threatening voice. "If I catch him, I'll break every bone in his body."