As Urubu paused, Biff appealed frantically to Ser-bot: "Don't let him shoot again-"

Serbot ordered Urubu to lower his rifle, which the guide did. At the same time, Urubu grinned, for he 104 .

had seen no ripple in the jungle leaves beyond the spot where he had first aimed.

"Perhaps," purred Serbot, "Urubu is trying to shoot an anaconda, the way he did the other day."

"Or some other jungle creature," added Pepito, over Biff's shoulder, "like those that we heard run away."

Biff guessed that they were trying to draw out facts from him, to learn if he and Kamuka had followed Luiz and listened in on the discussion that had shaped the later events. As Biff tightened his lips, determined not to answer, Urubu became impatient.

"And maybe," put in the leering guide, "I just now try to kill some person, the way Luiz was chased and killed."

"What happened to Luiz was his own fault," Biff argued hotly. "He tried to kill my father first, with a knife."

"Your bearers did not tell us that," stated Serbot smoothly. "We met them on their way back to Santa Isabel, and they told us that Whitman had fired at Luiz, who ran into quicksand-"

"Where we tried to save him. Did they tell you that?"

"Yes, they told us that. But not that Luiz had tried to kill your father."

"That happened before they even woke up. By then, Luiz had started to run, so naturally Mr. Whitman went after him."

BETWEEN TWO FIRES 105.

"The boy lies," snarled Urubu. "The bearers did not give you foolish talk like this."

"They gave us other foolish talk," reminded Ser-bot. "They scared our crew by saying there were Macus around here."

"But there are Macus around!" exclaimed Biff. "Their camp is only a few miles away from here. I know, because the Macus had me tied up as a prisoner all last night!"

The effect on Serbot's party was electric. Even before Urubu could translate the words to the bearers, they were dropping their packs, ready to take to flight, for they recognized the name "Macus" when Biff mentioned it.

But Serbot, raising his smooth tone to a surprisingly strong pitch, spoke in a mixture of Portuguese and native dialect that Biff managed to understand.

"Where will you go?" demanded Serbot. "Do you think you will be safe by running away like frightened deer, while the Macus are looking for just such prey? If there are Macus all around, as the boy says, there is nothing for us to do but go on and be ready for them!"

All this while, Pepito had retained his grip on Biff, but had been gradually relaxing the hold. Now, at Serbot's order, he released Biff entirely, but still kept a wary eye on him. Biff longed to dash into the jungle and look for Kamuka, but again he managed to restrain himself.

106 .

The chances were that Urubu's shots had missed and that Kamuka was lying low in the motionless foliage. To race after him and draw new gunfire would be the worst thing that Biff could possibly do. So he waited patiently until the safari started on.

Then Serbot took the lead, telling Biff to stay beside him, while Pepito guarded one flank and Urubu the other, all three carrying ready rifles. The bearers stepped along close together, eager to get through the Macu territory.

"Keep a sharp watch," Serbot told Biff. "The Macus caught you yesterday. Don't let them trap you again today."

Occasionally, Biff managed to look back, hoping that Kamuka had come from cover and was stealing along behind the safari. Soon Biff gave that up, realizing that if Kamuka had decided to follow them, he would be staying completely out of sight.

When they reached the spot where the Macus had bobbed up the day before, Biff recognized it. He turned to Serbot and said, "This is where the head-hunters were yesterday."

Serbot swung about and ordered the safari to halt. As the bearers set down their packs, Biff studied their faces and realized that some were members of the group that Whitman had organized, the natives who had started home when Joe Nara had exhibited the shrunken heads.

Their meeting with Serbot's safari must have scared some of Serbot's crew into going back to Santa Is- BETWEEN TWO FIRES 107.

abel. But Serbot or Urubu must have talked some of Whitman's men into coming along as replacements. Now Biff understood how Serbot had learned so much about Luiz.

After a brief rest, Serbot asked Biff, "Were there many head-hunters here?"

"Yes," replied Biff. "A lot of them."

"And which way did they take you?"

Biff pointed to the west. Smoothly, Serbot asked, "If there were so many, how did you manage to escape today?"

"Because most of them had left before dawn to go hunting," replied Biff. "That's why I was afraid of running into them."

"Good. We'll be on the watch for them."

Serbot ordered the safari forward. At the end of another mile, they came to a side trail, which cut sharply in the direction of the Rio Negro. After a rapid discussion with Urubu, so thick with dialect that Biff could not understand it, Serbot decided to take the river route.

As they started along it, Serbot spoke to Biff, using the smooth, easy tone that reminded Biff of their first meeting in the airplane above the Amazon.

"If the Macus are hunting along the main trail," declared Serbot, "they will never bother to come this way. That makes it all the safer for us. Anyone taking the main trail would be gone, for certain."

That was pa.s.sed along by Urubu to the bearers, who not only were pleased, but quickened their pace, 108 .

hoping to get out of Macu territory all the faster. But Biff's heart sank, for he was afraid there would be no catching up with his own safari now.

Then Biff noted that Serbot was studying him steadily. Evidently, the smiling man was anxious to learn which way the other safari had gone, and was hoping that Biff's change of manner would give the fact away.

Suddenly, there came an interruption that gave Biff a cause for real alarm.

"Listen!" he exclaimed.

From the treetops came a running chatter that seemed to carry like a wave from somewhere off in the jungle. Biff recognized the excited gabble.

"The howler monkeys!" he told Serbot. "That's the way they acted after the Macus shot some of them with arrows yesterday!"

Serbot tried to gauge the direction of the sound, then ordered the safari onward, faster. They followed the rough, irregular trail until they reached a spot where the chatter lessened and finally quieted altogether. Serbot waved for the bearers to set down their packs.

The order came just in time. The bearers themselves pointed to heads and shoulders that bobbed from behind trees and bushes. Terrified, the bearers shouted, "Macu!"

Serbot dived behind a pack, to use it as a shelter. Pepito and Urubu did the same, expecting Biff to join them with the huddling bearers, for spears, arrows, BETWEEN TWO FIRES 109.

and darts were now skimming toward them. Instead, Biff acted upon sudden impulse and raced along the jungle trail. He heard guns blast in back of him, but knew Serbot and the others were too busy shooting at the attacking head-hunters to worry about him.

Biff pa.s.sed a turn in the trail and knew then that he was safe from gunfire, but he had his eye on an opening in the jungle another hundred feet ahead. There, Biff was sure that he could duck from sight the way Kamuka had. But Biff was becoming too hopeful too soon.

Less than halfway to the spot, Biff halted in his tracks as the foliage parted and a painted Macu warrior loomed in sight. Armed with bow and arrow, the deadly marksman was already taking aim at Biff with his bowstring fully drawn.

Another moment, and the poison-tipped arrow would be in flight, allowing Biff no chance of escape at such close range!

CHAPTER XIII.

The River of Death THE tw.a.n.g of the head-hunter's bowstring was drowned by an explosive burst from farther up the trail. With it, the Macu marksman gave an upward, sideward jolt at the very instant the arrow was leaving his bow.

The feathered missile zimmed high and wide by a matter of scant inches, for Biff could hear it whirr past his ear and stop with a sharp thud in a tree trunk just behind him.

A piercing yell seemed to echo the timely gunshot. The Macu had dropped his bow and was gripping his left arm with his right hand as he dived off into the jungle. The bullet had jolted the bow from the Macu's grasp, sending the arrow wide.

Now, looking up the trail, Biff saw his father hurrying in his direction, rifle in hand. Biff started to meet him, shouting, "Dad!" only to have Mr. Brew-ster wave him back. Next, Biff saw his father take a quick shot at another Macu huntsman who had THE RIVER OF DEATH 111.

popped up in the brush, only to drop from sight again.

Now, from the other side of the trail, a brown head and arm poked from among a ma.s.s of blossoms that sprouted from the thin bark of a fallen tree trunk. Biff heard the familiar call: "Biff, come this way! Quick!"

It was Kamuka. Biff vaulted the log and took shelter behind it, but tried to shake off Kamuka's restraining hand as he saw his father come along the trail with Mr. Whitman and Jacome. All three were taking long-range shots at distant Macus.

"I have to warn Dad," Biff explained. "Serbot's party is just around the bend."

"He knows," a.s.sured Kamuka. "We were coming back when we heard their guns. So we hurry fast."

"Coming back along this trail?"

"That's right. When they couldn't find us on the main trail, they think maybe we take this one. So today, they take it to look for us."

"Then you sneaked ahead of Serbot's party after you ducked from sight. But how did you know to take this side trail when you reached it?"

"Jacome leave special message that I understand. Twist of gra.s.s and broken jungle branch are as good as mirror signal, sometimes."

Mr. Brewster and his fellow-marksmen had rifles with a longer range than the Macu weapons. Also, they were able to shift positions along the trail, preventing the Macus from picking a point of attack.

112 .

Serbot's party, on the contrary, had first let the Macus close in on them. Then, in solidly entrenching themselves, they had lost all chance of mobility. Soon they would have been surrounded if Mr. Brewster and his companions hadn't come along to scatter the foe. Kamuka called Biff's attention to that fact.

"Macu run like scared deer," said Kamuka. "But now your father is telling Mr. Whitman and Jacome to stop shooting. Why?"

"I guess Dad wants to keep the Macus around as a threat," returned Biff grimly, "until he sees what Ser-bot intends to do. Urubu might take a pot shot at anybody."

Kamuka gave a knowing nod. "You tell me!"

"Then you saw it was Urubu who fired after you?"

"Sure, Biff. I look long enough to see him aim. I tell Mr. Brewster all that happened, too."

Evidently, Mr. Brewster had profited by Kamuka's report. He had reached the bend where he was in direct sight of Serbot's entrenched party, but he was motioning for Whitman and Jacome to stay behind him.

Serbot looked up from behind a pack, then gave a wary glance in the direction the Macus had gone. A few arrows came whizzing from high among the tree boughs, but they landed wide. They were sufficient, however, to shape Serbot's next decision.

Serbot ordered Pepito and Urubu to resume their shooting after the Macus. At the same time, Serbot THE RIVER OF DEATH 113.

clambered over the packs and came along the path to meet Mr. Brewster, who in his turn ordered Mr. Whitman and Jacome to renew their fire on the distant head-hunters. Rifles barked in unison.

Biff and Kamuka joined their party in time to catch a last glimpse of the routed head-hunters.

"They won't stop until they reach their camp," declared Biff, "and maybe they'll still keep on going from there."

"Until they reach the Rio Negro," added Kamuka, "and maybe they swim it quick."

Mr. Brewster's meeting with Serbot resulted in an immediate, though guarded truce. Mr. Whitman and Jacome moved up to back Mr. Brewster, while Serbot was beckoning for Pepito and Urubu to come and join him. The boys stayed in the background as did Serbot's bearers, none of whom had been injured in the brief fray.

How many head-hunters might be lying dead in the brush or limping away wounded, there was no telling, but the battle had been won rapidly and effectively. Serbot seemed duly appreciative as he purred: "We owe you much, amigo. You have helped us. Perhaps there is some way we can help you."

"None at all," Mr. Brewster said curdy. "Now that we have driven off the Macus, we can go our separate ways."

"But how can you go anywhere? You have no bearers."

"They are waiting farther up the main trail, with 114 .

our equipment. We left them while we came back to look for the boys."

Serbot promptly raised a new line of inquiry.

"Perhaps you are surprised to see me here," he suggested, "So far from Manaus, where we last met."

"Why should I be surprised?" returned Mr. Brew-ster. "We are both looking for balata, aren't we?"

"I am not looking for rubber," Serbot declared. "I am looking for a man named Joe Nara, who claims to have a gold mine somewhere near the headwaters of the Rio Negro. He came down to Manaus in a fast boat shortly before you left your hotel."

"Who told you I had left?"

"The manager at the Hotel Jacares. He also said that your room appeared to have been robbed. The next day your jeep was found near an empty boat-house. I learned that Senhor Whitman had started from there on a rubber exploration trip upriver."

"And you thought I had joined him?"

"Exactly, Senhor. So I came by plane to find you."

Biff realized that Serbot's plane must have been one of those that had pa.s.sed over Nara's cruiser on the trip up the Rio Negro.

"After I hired Urubu as a guide," continued Serbot, "I learned that you had arrived on Nara's cruiser. So I a.s.sumed that you planned to meet Nara later."