“Jack, Jack,” he shouted, as he ran through the fog, blindly, but remembering to veer away from the river bank a little to avoid the danger of tumbling in. “Jack, Jack, where are you?”

A shadow, fog-distorted, loomed before him, big, enormous. A hand gripped his shoulder and brought him to a halt.

“Here I am, Bob. What’s the matter?”

Bob rubbed the back of a big hand across his eyes.

“I heard something out there,” he said, pointing into the fog upon the river. “I guess I’d been asleep, or daydreaming, anyway. I couldn’t be sure I had heard anything. It came twice—that sound. Then there was silence. So I came down here to ask whether you had heard, too.”

“But, Bob, what was it? What did you hear? I heard nothing.”

“Jack, it was the sound of a baby’s cry.”

Bob’s voice was solemn. A shiver ran through Jack, as if a breath of cold air had fanned him. In that fog-enwrapped isolation, in that far northern wilderness, what could a baby be doing? It was preposterous. More, it was uncanny.

“Bob, you were asleep. Yes, sir, you certainly were dreaming. A baby. Huh.”

“Maybe so,” Bob said, reluctantly. “But, true as I live, Jack——”

The other’s grip on his shoulder tightened.

Out of the fog came a wailing sound, distant, thin, but unmistakable. It was the cry of a baby, if ever there was such a thing.

But this time it came not from the river, but from inland. The two listened, straining to hear, but the cry died away without being repeated. They looked at each other, an unnamable fear gripping them.

“Jack, I’m afraid,” confessed Bob in a whisper. “I don’t know—there’s something strikes a chill into me—I—I——”

He paused. Jack nodded.

“I feel the same way, Bob,” he said, low-voiced. “What a pair of fools we are, though,” he added, brightening. “That must be some bird, or animal, perhaps.”

Almost unconsciously, they had been making their way southward and now another figure rose up in the fog before them—that of Frank. He was about to speak, when once more the wailing cry rose, and this time it came from two quarters, from the river and from farther inland. The three stood, silent, speechless, and in that moment, while the echoes of the cries still rang in their heads, Farnum and Art materialized out of the fog.

“Good, there you all are,” said Farnum, in a low, tense voice. “Follow me to camp.”

And without a word of explanation he started at right angles away from the river, for they had taken their stations in such fashion that Frank, holding the middle position, would be directly opposite the camp. This was in order to enable them to reach it without losing their way in the fog.

“What is it, Art?” asked Jack, his voice matching Farnum’s.

“Indians,” answered Art, tersely. “Stick close together and don’t make no noise.”

It was a situation to tax the nerve of the bravest, and the three boys hurrying along in the wake of Farnum and Art could not be accused of cowardice for experiencing a chill premonition of trouble ahead. Often had Farnum spoken of the cruelty of these far northern Indians. Bitter had been their experiences with Lupo’s half-breeds, in whose veins flowed the blood of the Indians of the north.

As they hurried along, there flashed through their minds some of the stories Farnum had told. Had they gotten so far, so near the end of their quest for the “Lost Expedition” only to be wiped out by Indians, on the very eve of success? Such thoughts raced through the mind of each. But they were determined fellows, accustomed to confront danger, used to tight places. The first onrush of panic was swept aside, and, by the time they tumbled into the little hollow in which camp had been pitched, and where Mr. Hampton awaited them, each had himself well in hand.

Mr. Hampton looked at their determined faces, and a smile of grim approval was his greeting.

“Indians, boys,” he said. “Farnum told me. I suspected as much. Now, we have no trees here for bulwark, but this little hollow is good enough. Let us lie down and line the edge of the pit. We’ll be pretty close together, and if any Indians stumble on us they’ll get a warm reception. Listen.” He spoke in a low voice. “There goes that cry again. Does it sound closer? Yes,” as the other nodded, “I thought so. Quick. Take your positions. Jack, my boy, you stay beside me.”

There was a little tremor in his voice. That was all. But Jack understood. He clasped his father’s hand strongly, then threw himself prone beside him, while the others ranged themselves in a circle as commanded.

Once more came the wailing cry from the inland. Once more it was answered in kind from the water. But to all it was apparent that the sounds were farther removed, and Mr. Hampton broke the painful silence with a whispered:

“They’re moving on, moving away.”

“Look, Dad,” Jack exclaimed excitedly. “I can see those rocks ahead where a minute ago was only the white fog. Why, the fog’s lifting. It’s lifting, Dad, sure enough.”

“You’re right, Jack,” his father replied, low-voiced, but there was anxiety rather than jubilation in his tone. “That will make it bad for us. We’ll be exposed to sight.”

Once again came the wail, faint and far away. As faint came the reply from the water. Both cries were to the north. Originally they had come from that direction. Now they were withdrawing whence they had come. What could it mean?

The next minute a rattle of rifle fire broke the silence. At the same time a cold breeze blew across the crouching figures in the shallow pit and the fog began to shred out fast before it.

Farnum sprang upright, gazing to the north. The others also gained their feet. The shooting now was fast and furious.

“I can’t understand,” said Farnum, in a puzzled tone.

With an exclamation, Jack seized his father’s arm.

“Dad,” he cried, “you said Thorwaldsson might be near.”

“Yes, why—”

“That’s it,” said Art, in a tone of conviction. Mr. Farnum turned towards him.

“You mean?”

“Jack guessed it. Thorwaldsson’s being attacked.”

Jack nodded.

“That’s what I meant, Dad.”

“You’re right, Jack,” said his father. “Come on. It can’t be anything else. Nobody but Thorwaldsson is in this wilderness. We must help him. Stick close together.”

And scrambling out of their shallow pit, Mr. Hampton started on the dead run towards the direction of the shooting, with the others at his heels.

The ground was bare of verdure, and great rocks of the copper ore were scattered around. On this account their view was restricted, but the sound of the rifle fire grew momentarily louder, apprising them that they were nearing the scene of conflict. Suddenly Bob, who was in the lead, having out-distanced the others several yards, rounded a big rock and found himself on a bank above a narrow strip of beach.

Below lay a number of forms, as of men dead or wounded. Two canoes were drawn up on the beach, and behind one of these, using it as a bulwark, crouched a man, rifle to shoulder. Farther down the beach were three other canoes grounded, and beside them several forms of wounded men, and five or six men, crouching, firing at the lone defender of the attacked position, creeping up on him.

Just as Bob reached the edge of the bank, the attackers mustered up courage for a rush, and with wild shouts swept forward. It looked dark, indeed, for the lone defender of the upturned canoes. Bob looked back to see how close were his companions, but they were not yet in sight. His dash had carried him farther than he had believed to be the case.

It had taken only a glance to show Bob which way the land lay. The lone defender was the survivor of Thorwaldsson’s party, if the explorer’s party it was, of which Bob had little doubt. He was a white man. The others were half-breeds, and if Bob was not mistaken they were of the same gang which he had encountered before.

It was distinctly up to him to lend a hand. Throwing his rifle to his shoulder, he prepared to open fire on the crushing enemy. But as his finger pressed the trigger, he groaned. The mechanism of the rifle had became jammed in some fashion. Desperately he worked to release the trigger, but to no avail.

Then the light of battle came into big Bob’s eyes. The half-breeds were just below him now. Several of their number had fallen in the rush, shot down by the defender of the canoes. Four were left, and they evidently were bent on polishing off their lone opponent. So absorbed were all in their own drama, they had not seen Bob.

Clubbing his rifle, Bob leaped. He came down on the back of one of the attackers, and bore him to the ground. With catlike swiftness, Bob, who himself had fallen on his hands and knees, gathered himself together, regained his feet, and swinging his clubbed rifle, let out a yell fit to “frighten a wolf pack,” as Frank later described it.

The stock of the rifle came down with a thud on the shoulders of another of the half-breeds, felling him as if he had been struck by lightning. So tremendous was the blow, that it tore the rifle from Bob’s grasp. But he leaped for another of the enemy, a fellow whose startled face was close to his, seized him about the waist and whirled him aloft to be tossed aside as if he were a sack of meal. The fourth man was dropped by a shot from the defender of the canoe.

“Attaboy, Bob,” came Frank’s voice, from the bluff above.

One after the other, Bob’s friends leaped to the beach.

As Frank and Jack clapped him on the back, and tried to grasp his hand, uttering enthusiastic praise the while, Bob looked around.

“Say, where’s that chap? Why, he’s fainted.”

Freeing himself from his companions’ clutches, Bob leaped over the up-ended canoe and bent above the recumbent body of the doughty defender.

“Why, he’s badly wounded,” he cried.

Mr. Hampton pushed him aside.

“Here, let me look, Bob,” he said. “You fellows help Farnum and Art in looking after the others. The place is a shambles, with wounded men everywhere.”