THERE was not a moment to lose. With the huge white condor swooping down upon them, the explorers knew that they must act quickly. Unfortunately their rifles had been left on the trail above. Before they could secure the weapons the huge bird would be upon them and would probably use its terrible claws and beak to great advantage.

“My knife is all we have to defend ourselves with,” said Joe, watching the large form advance toward them. “But I’m going to use it.”

The condor came on swiftly. It circled around a few times near its nest and then rushed madly at the little group of adventurers.

Now it was barely ten feet away and coming with deadly aim. In but a brief moment it would be in a position where it could work deadly havoc with its sharp claws.

Joe had his long hunting knife in readiness now, waiting for an opportune moment. Then it came.

The huge white bird was soaring directly above its human enemies. As it dropped lower, Joe lunged forward and plunged the sharp knife through one of the long, thin legs.

Uttering a curious sound, the condor darted away, circled around for a brief period, and then flew at the explorers with a new determination.

One of the horrible claws shot out and caught Joe’s arm, the impact knocking the knife from the youth’s hand. It went hurtling to the bottom of the abyss, far below.

Joe was weaponless, helpless!

New horror crept over him when he suddenly felt himself leaving the ground. Not fifteen feet away was the edge of the cliff! Vainly he tried to escape from the clutch of that formidable claw.

Meanwhile, Bob and the old man were not inactive. They knew that it would only be a short time before their friend would be carried over the brink of the cliff. And that must be prevented at any cost.

Looking wildly about, Bob caught sight of a rock about half as large as a brick. Almost frantic, he picked it up, and with desperate strength he sent it crashing into the condor’s body.

The force was terrific, and for a moment it seemed as if the condor were going to drop. But it righted itself and carried the helpless Joe still farther toward the rocky edge.

“I’m going to try something,” blurted out Bob, his face red with an awful fear. “You run up to the mules and get a rifle—quick!” he said to Dr. Rander.

As a last resort, Bob hurled his hundred and eighty pounds at Joe’s feet, and caught hold with a grip of steel. He wondered if the huge bird could lift both himself and his friend. If it could....

At that moment Dr. Rander scrambled down the rocky slope with a rifle, which he aimed unflinchingly at the condor’s body. The next moment the gun barked.

With a terrific fluttering of its heavy wings, the bird sank slowly to the ground. It touched the hard soil, and then with a convulsive twitch it lay still.

For almost a minute there was silence among the little party of adventurers. They were panting furiously, and their wide eyes had not yet lost their look of terror. Perspiration was streaming from them, making their faces shine gruesomely. It had been one of the narrowest escapes they had had so far.

Finally Joe wiped his face and looked at Bob with intense gratitude. Then his eyes fell on Dr. Rander, whose rifle was still warm from the timely shot.

“I don’t know how to thank you,” he said warmly. “If you hadn’t been so plucky, I would probably be lying in a broken mass at the bottom of the gorge right now. It was simply wonderful!”

“Forget it!” Bob disclaimed any praise offered him. “The only thing now that matters is that you’re alive.”

“Thank Bob for that,” the old man said. “If he had not thrown himself at your feet you would surely have gone over the cliff.”

“But it was your shot that finished the job,” protested Bob Holton. “Even with the weight of both of us the condor was slowly dragging us toward the brink.”

“I’m afraid my bullet would have been too late if you hadn’t done what you did,” persisted the old man.

“All right. Have it your own way.” With a laugh Bob dropped the matter and stooped over to examine the huge white bird.

It must have had a wing spread of over ten feet. Later measurements showed that this was accurate. But what impressed the youths most was its pure white feathers, which looked as clean as if they had been recently washed. The terrible claws and long sharp beak next caught the youths’ eyes, and their respect for the power of this monstrous bird was increased.

“Quite a specimen,” observed Joe. “And speaking of specimens,” he went on, “why can’t we skin it and take it with us? Our dads and Mr. Wallace would sure be tickled. The white condor! Boy! I can just see them giving cries of delight.”

“Nothing to prevent us,” returned the other youth. “We may find it hard to place in our mule train, but we’ll manage some way.”

Bob secured a long knife, and with a skill that he learned while on other hunting trips he cut the bird’s skin open down the breast. A few minutes more and the task was completed.

Without the weight of the body, the skin was light, and they had no difficulty in tying it over the back of one of the mules, which appeared not to notice the extra load.

With one last look at the spot where Joe had almost met his death, they turned and drove the pack animals ahead on the remainder of the journey to Pasaje.

But now they were more anxious than ever to reach their destination and fly with Karl Sutman to the place where their fathers were hunting. With every minute they longed still more to reach the town they were approaching.

“I hope nothing further comes up to stay us,” remarked Bob, as they descended a steep slope. “Somehow I’ve had enough excitement for a while.”

“So have I,” said Joe. “But of course there’s no way of telling what we may meet in these mountains.”

The next day they found themselves in a wide valley, which was covered with a heavy growth of dense vegetation. Tree ferns were quite prominent, growing in large clusters that dotted the valley. Bright flowers were also numerous, some of them unusual in shape and form.

And with this heavy vegetation came several varieties of wild animals, among them being foxes, lizards, guinea pigs, and a host of birds. The youths could easily have shot some, but they did not wish to lose time in doing so.

“I believe we are getting close to Pasaje now,” announced the old man, as he led the way around the winding Apurimac River.

Notwithstanding this, they traveled all that day without coming to the town. Camp was made at a clearing near the stream, supper was prepared, and then all retired, knowing that the following day would witness their coming to their destination.

Early the next morning the young men saw something that thrilled them with delight. They had been breaking camp and were almost ready to resume the tramp when suddenly their keen ears caught the sound of a motor. Looking up, they plainly made out an airplane in the sky above them.

“That’s Karl!” cried Joe joyously. “I wouldn’t be afraid to bet anything that it is.”

“I sure hope you’re right,” came from Bob. “Gee! Won’t it be swell to see him again?”

“Of course there’s a chance that he won’t see us,” said the other boy. “But I believe he will. He’ll be looking around for us closely. Maybe that’s why he’s here now.”

Bob started, as an ominous thought struck him.

“Do you suppose anything’s happened—to our dads, I mean?” he asked in a tense voice.

Joe’s face darkened.

“I—I hadn’t thought of that,” he replied solemnly.

They watched the airplane closely, expecting at every moment to see it head downward.

Then it came.

“Hurrah!” Bob was overjoyed. “Karl sees us, all right. And it’s Karl, too,” he observed, as the monoplane came closer.

As the machine flew closer it circled around the little group below, rapidly flying lower. When within a hundred feet of them, its cabin window opened, and Karl’s face was thrust out.

“Hello, up there!” shouted Bob, and received an answering greeting. But the noise of the ’plane’s engine made it impossible for the adventurers to understand the aviator’s words.

While the three were still gazing up at the huge monoplane they saw something that caused them to look all the closer. They made out Karl’s arm reaching out of the cockpit. Then they saw something white drop toward the ground.

“It’s a small parachute,” observed Joe, his heart beating rapidly. “Wonder what’s tied to it?”

As there was no wind, the object fell in a straight line, the parachute opened and began to float slowly above the onlookers. Before long it came to the ground within fifteen feet of them. Karl had certainly aimed accurately.

“Hurry!” cried Joe. “Let’s see what it is. Maybe something’s happened to our dads or the others.”

He picked up the parachute, at the end of which was attached a small box. Opening it, the youth found a folded paper.

“Quick!” murmured Bob. “Let’s see what he has to say.”