Back up the stairs they sprang. They were just in time. Two of the Mexicans came up the stone steps into the gallery. They paused by the landing and stood for some time engaged in conversation. Of course while they should remain there the way was blocked for Frank and Barney. The two fugitives were dismayed. They knew that at any moment the miners might return to their work and then their escape from the old shaft would be discovered. Even as this fear was upon them, Frank heard a commotion in the gallery above. A loud cry in the Mexican tongue came down from above. The effect was startling. Instantly the greasers below sprang up with loud cries, and made a rush for the galleries. Frank turned to Barney. The truth had burst upon him with horrible force. “My God!” he gasped. “We are lost, Barney. They have discovered our escape!” “Begorra, that’s thrue enough,” agreed the Celt. “Phwat shall we do, sor?” For a moment Frank was in a quandary. But there was no time to lose. The Mexicans were swarming up into the galleries. To retreat into the shaft from which they had emerged would be folly. But where else could they go? It was a serious question. There was no time to lose. Suddenly, at that moment, Frank saw a narrow opening in the gallery wall. He rushed into it and found that he was in one of the many passages which made a honeycomb of the hill. All was darkness, but the young inventor did not care for this, so long as safety was assured. Barney was close behind. They were just in time to avoid being seen by the foe. Fortunately not one of the Mexicans turned into this passage. “Thank Heaven, we have given them the slip for a moment,” Frank breathed. “Bejabers, I’ve an idea!” exclaimed Barney, with eagerness. “Indeed!” said Frank. “What is it, Barney?” “Shure, sor, let us stay here by the opening. Pretty quick the blathershites will all be gone by. Shure, thin, we kin slip out av here, an’ p’r’aps foinde our way out through the main passage. Do yez see?” “There is logic in your plan, Barney,” declared Frank. “I think we will try it.” Accordingly the two fugitives waited for their pursuers to pass. Soon they were heard in the upper gallery, and it seemed as if the coast was clear. “Bejabers, now’s our toime,” cried Barney. “All right,” agreed Frank. “Let us try the game.” “Will yez lead the way, and I’ll folly, if it is to perdition?” “I will.” Frank crept out into the gallery. He cast a glance up the gallery and saw nobody. But as he looked in the other direction he was given a mighty thrill of horror and dismay. There, not twenty feet below, stood half a dozen of the greasers. They blocked the passage, and what was worse at that moment, they saw Frank Reade, Jr., and gave a yell of discovery. It was echoed in the gallery above, and then exciting scenes followed. Frank darted back into the passage. He was not a moment too quick.