“Come on, get the lights out,” Mills growled.

“Sure, nobody can see a light in here now,” Red added. He did not produce a flash himself, but two of the men in the rear did, sending the rays on the floor of the trail. On they went at a quicker pace.

At times the forest cave lead them down steep declivities where it was evident to the Flying Buddies that the enclosure was made by hand, not nature, although she had helped. Another time they were walking forward on a woven floor and through the loosely secured vines they caught glimpses of sparkling water which pounded against the rocks that confined it and sent a spray so high that the place was spongy and wet. Later they were close to the surface of the stream and the boys guessed its bed was an underground passage. At this point the route turned sharply to the left and presently the flooring ended; they began to ascend a gradual incline which they judged was a circuitous path through some rugged section of the country.

It seemed to Jim that they must have been going for hours. His feet were beginning to tire and his calves felt as if every muscle was strained. He wondered about the Indians they had seen before the bandits came down in their plane and marveled more and more that nothing was done to impede progress. By that time they began to climb, and now the foliage was more dense, the air grew hot and stifling, as if the enclosure had not seen the light of day in many generations. Thinking it over the boy concluded that this route was rarely used and it certainly was not so well constructed as the hidden trail from Cuzco which he had traversed months before. In the first place, that was both light and the foul air driven out, then he remembered that it was cared for by the men in the great Amy Ran Laboratories from which it was constantly purified.

Austin tried hard to keep his mind clear and reasoned that perhaps Lang had in some way discovered the bare spot in the vast Andean forest, and may have investigated it, or he may have learned of it while working for the Big Boss. Then, overcome with greed, he had organized this handful of men to explore with him, calculating that the haul they would make would give each greater wealth if they were not forced to divide what they found with the whole organization. It struck the boy as odd that so many of the gang members had started out on their own, and each must have been thoroughly convinced that untold wealth lay at the end of this “rainbow” and they were eager to risk their lives in pushing their own discoveries to the limit. It was disquieting to realize that such a number of small groups were viciously determined to fathom the Don’s secrets and reap the benefits of the riches which rumor carried like wild fire among the outlaws.

Following the wiry Red, Caldwell marveled at the strength of the little man who leaped briskly ahead as energetically as when they first entered the opening. Through his mind ran a series of plans for their escape but with arms bound, ropes held by grimly determined gangsters who doubtless had guns ready to fire at the first false move, the situation appeared utterly hopeless. He, too, was beginning to feel fatigue, his feet seemed weighted with lead, and his head and lungs ached from the foul air. Occasionally he glanced back at Jim, who kept as close as possible, but they spoke no word as they went on and on. At last the journey was telling on all of the men, for their panting breaths were coming in painful sobs. Even Red faltered; twice he slipped and almost fell flat, but he managed to recover himself.

“Better let someone else take the lead,” Lang proposed.

“Better stay where you are,” Red snapped angrily. Nothing more was said, then the boys began to wonder if any of the gang would drop out from exhaustion, but as far as they could tell, none had. Then one of the lights grew dim, and Red cursed.

“Change your battery.” This was done, and soon they were going on swiftly, but there was a steep climb ahead. With difficulty it was finally negotiated, but it took nearly half an hour. At last they were all on the top. The place looked as if it crossed, or followed a high ledge, the wall which was moss grown formed one side, while the other was slanting, like a shed roof. Again they passed over a stream, but it was a mighty dangerous undertaking, for great holes yawned beneath them, and Red managed to make it by hanging on to the vines above him.

“We can’t catch hold,” Jim protested.