As Bob Caldwell pursued his botanistic observations along the edge of the dense forest, his mind was filled with keen regret that he could not spend several weeks in the neighborhood with plenty of reference books to aid him in recognizing the numerous varieties of vegetation which surrounded him, and he also regretted the fact that they had found the old Indian, or whatever he was, in the neighborhood because of course that meant that the spot was not so isolated as it appeared and in all likelihood there were others living close by. But for the appearance and disappearance of the mysterious old man the Flying Buddies would not have felt the need of such caution and he could have been confident that it was safe to penetrate a little way into this paradise of tropical growths and perhaps find something they could take back to Texas. It was disappointing, but at the same time he had to admit that it was doubtless better that they had discovered him immediately; better than thinking they were secure then running into a hostile tribe without warning.

Since they had come to South America the Buddies had encountered so many dangers in wild, out of the way sections that it had developed their bumps of caution to a high degree. To be sure the authorities had quietly ascertained that Arthur Gordon was still laid up with a broken leg at the home of the doctor who had taken him in charge after the accident in the snowy fastness of the Andes, and Ynilea, the Laboratory man at the Don’s had said that the Big Boss, frightened at the repeated disasters which had befallen many of his men and undertakings, had taken himself out of the country, but the Sky Buddies were convinced that this chap, whoever he was, had made up his mind to fathom the secrets and secure possession of the vast wealth. While the loss of a few lives might make him get away, to save his own skin, he would probably recuperate his weakness, reorganize his band and start in again at the first opportunity.

“The Big Boss, I reckon would get back to the United States, or to his own hangout, wherever it is, cure himself of his scare, then begin all over again. Getting possession of unlimited wealth, he’ll figure, isn’t to be passed up, and this time he’ll cook up some schemes that may work better than the others.” Bob grinned to himself at the idea, then through his brain flashed the memory of the wonderful laboratories with their numberless workers and scientific advantages. “Then again, maybe they won’t. I’m betting my dimes on the Don.”

With that comforting assurance, Caldwell turned his attention to his job, moving slowly and occasionally glancing across to where his step-brother waited patiently beside the plane. He thought that Jim was mighty decent to hang around doing guard duty when he would probably have liked to do some studying himself, and resolved to cut his observations as short as possible. With that in mind he snipped leaves, tiny branches, bits of root, and made rough notes to which he could refer later when there was more time. Nearly two hours had been consumed and the younger boy had made half the circuit when he reached a section where there were almost no large trees, although those which grew on both sides were so heavy with branches and foliage that the arch above was as thick as a roof. In the space there seemed to be more fallen trees and rocks than elsewhere. Besides, there was a good deal of young growths, slender saplings and brush, also rather a heavy hanging, like a great curtain of vines suspended from the limbs above. The appearance of this semi-clearing made Bob suddenly remember the way they had once gone to the Laboratory with Ynilea. That day, the party had started from Cuzco by automobile, left the main thoroughfare, traversed an unmarked route over rocks and foot hills, finally leaving the machine and making their way through a well-concealed natural hallway until at last they came out on a ledge from which they were taken in a strange airplane the rest of the journey.

“Great Christoper’s ghost, wonder if this is another of those hidden ways,” he exclaimed excitedly, and forgetting for the moment the need to be cautious, he stepped on to a broken stump in among the protecting curtain. But, before he could advance another inch, his quick ear caught a sharp whistling sound which he thought must have come from Jim’s lips, but before he could turn about, something dark cut in under his arm, hit the nearest sapling and drove like the blade of a stiletto clean through its heart. The young tree quivered from the impact and in an instant tiny beads of sap oozed from the wound.

“Whew—” Bob waited a moment, too startled to think, then he managed to turn about, and his eyes nearly popped out of his head. In the first place, it seemed to be snowing for the air was filled with fluttering white things which seemed to be struggling to go on, and although they looked like butterflies, the boy was sure he must be mistaken for he had never seen nor heard of anything like it. Through the queer storm he could see Jim crouched near the helicopter, the looped lariat hanging from one hand and his mouth open as if he had been about to yell a warning which had frozen on his lips. Quickly Caldwell’s eyes swept to where Jim’s were staring and instantly he understood from whence the murderous dart had been driven. He saw the three Indians, two of them facing him while the third had his gaze fixed on Austin. One of the men held a second dart in his hand and was slowly raising it above his head prepared to send it with deadlier aim than the first.

Then, as if some supernatural power had intervened, the fluttering white things dropped thickly into the space, completely filling it with their bedraggled bodies and helpless beating wings. As Bob stood a bit back in the protection of the swinging vines it was like observing the strange spectacle through a window. None of the insects landed within a couple of feet of him, but beyond the air was like a swirling blanket which effectively cut him off from sight of the Indians plainly determined to kill him. Anxiously the boy wondered about Jim, for he could no longer see anything but the butterflies, and through his mind raced half a dozen plans.

Bob thought of running out to his step-brother, but hesitated about doing that lest Austin endeavor to reach him among the vines. Thinking it over, in a moment the lad decided that his Buddy’s best bet was to remain near the machine. Probably, safely hidden from the view of the Indians he could climb into the cock-pit and prepare to take immediate flight, then Bob wondered if the mass of insects would interfere with a take off. With thousands of them tumbling about the plane their tiny bodies might clog the engine, propeller, and lifting wings, besides making it practically impossible for the pilot to tell in which direction to start.

Recalling the position of the plane when they landed, Bob realized that if the butterflies had done no damage the helicopter could mount without difficulty in the limited space, keep climbing until it was above the danger zone and they would be safe. With this fact in mind, he determined to get to the machine without further loss of time. It would take only a few minutes to be a safe distance from the Indians who could do nothing more until the air cleared. Then he recalled that the natives were doubtless familiar with the locality, they were the best woodsmen in the world, and the three might, even now, be making their way to him. The idea wasn’t a cheerful one, and Bob turned his eyes in the direction he thought he had left his Buddy, then stepped forth. He had hardly reached the edge of the waving vines when he heard the unmistakable, although muffled roar of an engine and guessed that Austin was all set to go, but he was surprised that the sound seemed to come from further south than he had calculated. This fact made him pause to make sure, then, at his left he heard a noise of someone running. It might be one of the Indians so he drew back quickly.

“Buddy, I say, Old Timer, where are you?” It was Jim, not one of the natives, and Caldwell sighed with relief.

“Here,” he answered.

“Good.” Jim leaped beside him grinning broadly.

“Wow.”

“I wasted a lot of time running around the edge but I was afraid of missing you,” Austin panted.

“I heard the engine going—”

“No you didn’t, not ours,” Jim answered.

“But come along and we’ll get it going.”

“Must be another plane around here.”

“Reckon there is and it may be as well if they do not see us,” the older boy responded. “Great guns, these butterflies are life savers all right.”

“Then some. It’s like a nightmare.”

“Put your hand over your mouth so you don’t swallow a carload.” Bob followed directions, and the Buddies bent forward prepared to start, but by that time the approaching plane was making a thunderous noise for it was above the clearing, then its motor was silenced.

“They are coming down, Jim. Think we’d better stay here?” Bob suggested. “We can hide out further in the forest.”

“Reckon our best bet is to get to the machine,” Jim answered, but then the plane came down so close to them that they could see its huge bulk only a few feet away. To get by it without being seen would mean some maneuvering and good luck aplenty. The boys scowled, but Austin motioned to proceed, so they stepped forth, bending low and praying that the newcomers would not look about them immediately.

“These blasted bugs,” one of them swore roundly.

“They gummed the works,” added another. There were half a dozen passengers in the plane who climbed out of the cockpit on the further side, then one of them called:

“We’re right where we want to be.”

“Good work,” came a more cheerful response.

“Good pilot you mean,” spoke up one.

“Pilot nothing, up in that buggy blanket you didn’t know your prop from your tail; whether you were going or coming, upside down or right. Rotten piece of piloting gunning into a flock like that.”

“I did not go gunning into them. The things came along so thick I couldn’t get out of them. They got all over the plane and plastered everything, look at it, even my goggles are covered with them. I got you down without a smashup, didn’t I? You can thank me that you’re not hash—”

“Well, I’m not thanking you,” the other retorted, then added with an oath, “and if you had busted the plane, I’d a pumped you full of lead, see. You can thank me that you aren’t a sieve this minute.” During this disquieting dialogue the boys had made little progress, then suddenly a voice shouted.

“I say, who else are you expecting?”

“Nobody, you know very well.”

“There’s a plane here—”

“A plane?”

“Yeh. One of those whirligig ones.” At that announcement the boys stopped in their tracks.

“Let’s go back,” Bob whispered, tugging at Jim’s coat.

“This is a hard crowd,” Jim admitted. They started to retrace their steps but by the time they reached the fallen logs, the air was almost clear, the live insects had struggled on, while only a few who could go no further, fluttered to the ground, which was white with their fallen mates. Instinctively Bob’s eyes sought the spot from which the dart had been thrown at him, but it was empty; there wasn’t a native in sight, young or old.

“They are gone,” he gasped in astonishment.

“Look who’s here!” The Flying Buddies had been discovered by one of the gang, and a tall ugly looking customer who carried a gun in his hand, turned quickly. “Our welcome guests.”

“What are you doing here?” the tall fellow snarled.

“Dropped down very much as you did, I reckon,” answered Jim.

“Bugs drive you out of the sky?” This was probably the pilot who had just been driven out himself.

“Like blazes. That motor hasn’t been running lately. If the bugs forced you down, what you doing over here? Come on, speak out, and reach for the sky, while the reaching is good,” came the sharp command.

“Aw, be yourself,” Bob retorted angrily. “I’m not reaching to anything for a goof like you—”

“Aint you—” The gun pointed threateningly, then one of the men interposed sharply.

“Put it down, Mills.” It was the smallest man in the crowd who gave the order and he strode forward. “What you fellows doing here?”

“Came up to study the vegetation,” Bob replied firmly.

“Yeh. Well now, that’s nice. Where do you hail from?” Jim’s foot sought his step-brother’s, but Caldwell did not feel the pressure.

“Texas,” he answered, and immediately he wished he hadn’t been quite so specific.

“Couple of flying cowboys. Well, you’ll never know how glad we are to find you here,” the man sneered.

“Oh, don’t mention it,” Caldwell answered with a cheerful grin, but both of the boys were wondering what new mischief was afoot.

“I won’t mention it outside of our little circle of friends here,” the fellow promised. “Nobody’ll ever be able to say we run across you in these parts. It’ll be our little secret.” He turned to his companions. “Remember that, men, this happy meeting aint to be whispered to any naughty inquirer.”

“Sure. Now, give us the dope.”

“It’s the—as I said before, THE kids we need in our business, see! Be sure you see, and hear.”

“Gee, aint we got luck!”

“The Don’s own little pets.”

“Waitin’ fer us. Aint that thoughtful now.”

“Hope we didn’t detain—”

“Shut up,” snapped the little man, then turned to Bob. “What you doing here?”

“I just told you, studying the vegetation.”

“Yeh, well that stuff don’t go with us. These here Honduras is full of vegetables, see, you don’t have to come way up here.”

“We were flying and saw this clearing so we came down. Whether the ‘stuff’ goes with you or not, it’s the truth. My brother is interested in things that grow out of the ground and we looked for a place where—” Austin started to explain, but was cut short.

“You mean you was lookin’ fer this place.”

“No we were not. Have a look at my specimen book if you want to see for yourself what we are doing.” Bob proffered the book which was bulky with the things he had gathered and the small man glanced at it indifferently.

“That’s a stall. Now, you got something in your possession we want; that tube of reports. Fork ’em over pronto.”

“We haven’t a tube of any kind,” Jim answered.

“No? Search ’em boys.” This was done roughly and thoroughly but not a tube did they find and they scowled when they finally had to admit defeat.

“Go through the plane,” the tall man proposed. At this the pilot and two others raced to the machine, and in a moment it was being subjected to an overhauling that promised to leave it a wreck.

“Can’t find the thing,” the pilot shouted.

“No?” The little man drew his gun. “Now, you know what we mean. Where is that tube?” He pressed the weapon to Jim’s belt and his rat-like eyes blazed with anger. “Where is it?”

“We did have a tube,” Bob answered.

“I know you did and you still have.”

“You are just as much mistaken as if you’d burned your shirt. We had a report tube we were taking home to Jim’s father, but you’re all wet—too late—”

“What do you mean?”

“It has already been stolen,” Bob told him.

“Stolen! Who the—” The men were crowding around now and every face was ugly.

“By a friend of yours, I reckon,” Jim drawled.

“Friend, hey—” The man whirled on the members of his gang.

“Turn that gat, you fool—”

“Who took it?” the little man thundered.

“Gordon, fellow named Arthur Gordon,” answered Bob.

“Gordon, who the blazes is Gordon?” demanded one of the gang.

“I know him,” the tall man answered.

“So do I, blast his hide. When did he steal it?”

“Day before yesterday. We were coming north; he passed over us in a big plane, dropped on the wings and drove us off the course. We landed up in the snow, had a fall, and he robbed us—”

“Yeh. Say, tell that to the marines. Gordon wasn’t risking his neck by dropping on you out of another plane,” the tall man objected.

“Then let you get away. You got to make up a better story than that, bo, see!”

“I do not need to. Gordon hurt himself and is laid up with a broken leg—”

“If he snitched the tube, then you got it back—”

“We didn’t get a chance,” Bob declared.

“Say, we’ll fix ’em so they tell better stories. Tie ’em up boy with them lariats and do a good job. They got out of some tight holes, but the fellow that lets ’em get away this time gets plugged, see.”