The boys planned to go on a trip to Golden Peak the next day, but decided to go hunting instead, and, as Billy pointed out, they had over a week before the waters would rise and cover the hill.
Meanwhile Mr. Thornton carried out his plan. A big gang of men assembled at the dam, and soon began the work of finishing it. It was decided to build up the concrete work, and set the many water gates. Then, when the cement had set, all that would be necessary to do would be to close the gates against the river, the water would begin to back up, and the lake would form.
A search had been made for the missing man, but he had not been found. The men who had been on guard at Golden Peak had also disappeared, and the place was in possession of the forces of the ranch owner.
"I guess they're not going to trouble you," said Frank, one day.
"I'm not so sure of that," replied Billy's uncle. "This may be the calm before the storm. I'm always suspicious when such men lay low and do nothing. They're preparing for a big move, I have no doubt; but I'll be ready for them. They've got one advantage on their side, in possessing that paper, but I'll have the dam built and the lake over their property before they can act, I hope."
Men guarded the dam day and night. In fact the work went on at night, by means of the light of flaring gasoline torches.
The gap was nearly closed. The gates were all in place, and only a few more yards of concrete and rubble needed to be dumped in.
"If you fellows are going to get the treasure of Golden Peak you'd better get a move on," said Mr. Thornton, dryly, to Billy and his chums one night.
"Why?" they asked. They had been so busy having a good time, hunting and riding over the prairie, that they had almost forgotten about it.
"Because," answered the ranch owner. "I expect to close some of the gates to-morrow, and soon flood the region. Golden Peak will be out of sight in two days more."