"It's going down!" cried Bud, for there was no longer any advantage in concealment or silence, as long as Del Pinzo and the others had fled. "It's receding!" "Just as the other did!" added Dick. "They must have opened a gate here and let the water out!" "They've done something!" cried Bud, "and we've got to find out what it is." "Did you hear that about a fuse?" demanded Snake. "Maybe they're going to blow the place up!" "If they do, and the tunnel caves in, good-bye to my water!" said Bud. "Yes, and good-night to _us_!" grimly added Old Billee. "Come on!" cried Yellin' Kid. "Let's see what's up there in that hole in the wall, anyhow!" "And have your guns ready!" warned Snake Purdee. However, as it developed, the weapons were not needed. When the boy ranchers and their friends managed to scramble up the rocky way, above and to the right of the second hidden, branching stream, and found themselves in what was virtually a little natural recess hollowed out of the rocky wall, they saw that it was deserted. But there were plain evidences of the fact that the men they had seen had fled in a hurry, as, indeed, they had practically witnessed. Playing cards, cigarettes, tobacco and bottles were scattered on a rude wooden table, and there were several candle-ends stuck in the necks of flasks. The smell of the extinguished candles was heavy on the air. "But where did they go?" asked Bud, when a hasty glance around the rocky room disclosed no occupants. "What's that?" asked Dick, pointing to what seemed to be a hole in the floor at one corner. "It's a passage!" cried Billee, holding his lantern above it. "An' big enough, even for me! I'm going down!" "Will it be safe?" asked Nort. "It may lead into the stream, or to where they have planted a mine--they spoke of a fuse----" "You've got to take chances in times like these!" declared Old Billee. "I guess if they went down it will suit us." "Unless they can close it up, or turn water in," suggested Snake, dubiously. "Git out! I'm going down!" stoutly declared the rather fleshy veteran cow puncher, and when he let himself down the hole the others followed. There was a natural stairway, or what served the same purpose, leading down out of the stone room where the conspirators had been evidently plotting so far underground. The passage went down, at first, like a flight of steep, cellar stairs. Then it straightened out, and, after twists and turns, led upward. "Where are we going?" asked Nort. "Nobody knows!" grimly answered Bud. "But it's safe so far!" "And we're right on their trail!" added Snake. "How do you know?" asked Billee. For answer Snake paused and pointed to a smouldering cigarette stub on the rocky floor of the passage that had led out of the conspirators' niche. "That wasn't dropped many minutes ago," declared the cowboy. "They came along here."