"Look here," Chester went on, "that would be a reason for the train robbers hanging to father, if they found him, wouldn't it?"
"I don't understand," replied Will.
"Why, if father knows a lot of passages and hiding places and empty river channels, in this section, he's just the man the train robbers would want to tie to."
"I understand now," Will replied. "And you remember, too," he continued, "how mysteriously the three men disappeared last night? Why, they got out of sight as quickly as if they had been painted on a slate and rubbed out."
"That's a fact!" replied Chester.
"There's one thing about it," Will argued, "the train robbers won't dare to go on into the bad lands, for they have no supplies, and their horses must be about used up. By remaining here, they may be able to steal supplies and, possibly get out to Lander and buy some."
"I guess we've got it doped out all right," Chester answered. "All we've got to do now is to go on and see whether we have or not."
The boys pressed on to the back of the first cavern and turned to the right into one which ran parallel with it. Their lights showed that a fire had been built in the tunnel connecting the two. There were also empty tin cans and cardboard food packages scattered about.
"This looks like population," grinned Will.
"Isn't this the spot from which the men disappeared?" asked Chester.