Von Horn cursed the chance that had snatched the girl from him, but he tried to content himself with the thought that the treasure probably still rested in the cabin of the Ithaca, where Bududreen was to have deposited it. He wished that the Dyaks would take themselves off so that he could board the vessel and carry the chest ashore to bury it against the time that fate should provide a means for transporting it to Singapore.

In the water below him floated the Ithaca's masts, their grisly burdens still lashed to their wave swept sides. Bududreen lay there, his contorted features set in a horrible grimace of death which grinned up at the man he would have cheated, as though conscious of the fact that the white man would have betrayed him had the opportunity come, the while he enjoyed in anticipation the other's disappointment in the loss of both the girl and the treasure.

The tide was rising now, and presently the Ithaca began to float. No sooner was it apparent that she was free than the Dyaks sprang into the water and swam to her side. Like monkeys they scrambled aboard, swarming below deck in search, thought von Horn, of pillage. He prayed that they would not discover the chest.

Presently a half dozen of them leaped overboard and swam to the mass of tangled spars and rigging which littered the beach. Selecting what they wished they returned to the vessel, and a few minutes later von Horn was chagrined to see them stepping a jury mast-- he thought the treasure lay in the Ithaca's cabin.

Before dark the vessel moved slowly out of the harbor, setting a course across the strait in the direction that the war prahus had taken. When it was apparent that there was no danger that the head hunters would return, the lascar came from his hiding place, and dancing up and down upon the shore screamed warlike challenges and taunts at the retreating enemy.

Von Horn also came forth, much to the sailor's surprise, and in silence the two stood watching the disappearing ship. At length they turned and made their way up the stream toward camp--there was no longer aught to fear there. Von Horn wondered if the creatures he had loosed upon Professor Maxon had done their work before they left, or if they had all turned to mush as had Number Thirteen.

Once at the encampment his questions were answered, for he saw a light in the bungalow, and as he mounted the steps there were Sing and Professor Maxon just coming from the living room.

"Von Horn!" exclaimed the professor. "You, then, are not dead; but where is Virginia? Tell me that she is safe."

"She has been carried away" was the startling answer. "Your creatures, under the thing you wished to marry her to, have taken her to Borneo with a band of Malay and Dyak pirates. I was alone and could do nothing to prevent them."

"God!" moaned the old man. "Why did I not kill the thing when it stood within my power to do so. Only last night he was here beside me, and now it is too late."

"I warned you," said von Horn, coldly.

"I was mad," retorted the professor. "Could you not see that I was mad? Oh, why did you not stop me? You were sane enough. You at least might have forced me to abandon the insane obsession which has overpowered my reason for all these terrible months. I am sane now, but it is too late--too late."

"Both you and your daughter could only have interpreted any such action on my part as instigated by self- interest, for you both knew that I wanted to make her my wife," replied the other. "My hands were tied. I am sorry now that I did not act, but you can readily see the position in which I was placed."

"Can nothing be done to get her back?" cried the father. "There must be some way to save her. Do it von Horn, and not only is my daughter yours but my wealth as well-- every thing that I possess shall be yours if you will but save her from those frightful creatures."

"The Ithaca is gone, too," replied the doctor. "There is only a small boat that I hid in the jungle for some such emergency. It will carry us to Borneo, but what can we four do against five hundred pirates and the dozen monsters you have brought into the world? No, Professor Maxon, I fear there is little hope, though I am willing to give my life in an attempt to save Virginia. You will not forget your promise should we succeed?"

"No, doctor," replied the old man. "I swear that you shall have Virginia as your wife, and all my property shall be made over to you if she is rescued."

Sing Lee had been a silent listener to this strange conversation. An odd look came into his slant eyes as he heard von Horn exact a confirmation from the professor, but what passed in his shrewd mind only he could say.

It was too late to attempt to make a start that day for Borneo, as darkness had already fallen. Professor Maxon and von Horn walked over to the workshop and the inner campong to ascertain what damage had been done there.

On their return Sing was setting the table on the verandah for the evening meal. The two men were talking, and without making his presence noticeable the Chinaman hovered about ever within ear shot.

"I cannot make it out, von Horn," Professor Maxon was saying. "Not a board broken, and the doors both apparently opened intentionally by someone familiar with locks and bolts. Who could have done it?"

"You forget Number Thirteen," suggested the doctor.

"But the chest!" expostulated the other. "What in the world would he want of that enormous and heavy chest?"

"He might have thought that it contained treasure," hazarded von Horn, in an innocent tone of voice.

"Bosh, my dear man," replied Professor Maxon. "He knew nothing of treasures, or money, or the need or value of either. I tell you the workshop was opened, and the inner campong as well by some one who knew the value of money and wanted that chest, but why they should have released the creatures from the inner enclosure is beyond me."

"And I tell you Professor Maxon that it could have been none other than Number Thirteen," insisted von Horn. "Did I not myself see him leading his eleven monsters as easily as a captain commands his company? The fellow is brighter than we have imagined. He has learned much from us both, he has reasoned, and he has shrewdly guessed many things that he could not have known through experience."

"But his object?" asked the professor.

"That is simple," returned von Horn. "You have held out hopes to him that soon he should come to live under your roof with Virginia. The creature has been madly infatuated with her ever since the day he took her from Number One, and you have encouraged his infatuation until yesterday. Then you regained your sanity and put him in his rightful place. What is the result? Denied the easy prey he expected he immediately decided to take it by force, and with that end in view, and taking advantage of the series of remarkable circumstances which played into his hands, he liberated his fellows, and with them hastened to the beach in search of Virginia and in hopes of being able to fly with her upon the Ithaca. There he met the Malay pirates, and together they formed an alliance under terms of which Number Thirteen is to have the girl, and the pirates the chest in return for transporting him and his crew to Borneo. Why it is all perfectly simple and logical, Professor Maxon; do you not see it now?"

"You may be right, doctor," answered the old man. "But it is idle to conjecture. Tomorrow we can be up and doing, so let us get what sleep we can tonight. We shall need all our energies if we are to save my poor, dear girl, from the clutches of that horrid, soulless thing."

At the very moment that he spoke the object of his contumely was entering the dark mouth of a broad river that flowed from out of the heart of savage Borneo. In the prahu with him his eleven hideous companions now bent to their paddles with slightly increased efficiency. Before them the leader saw a fire blazing upon a tiny island in the center of the stream. Toward this they turned their silent way. Grimly the war prahu with its frightful freight nosed closer to the bank.

At last Number Thirteen made out the figures of men about the fire, and as they came still closer he was sure that they were members of the very party he had been pursuing across the broad waters for hours. The prahus were drawn up upon the bank and the warriors were preparing to eat.

Just as the young giants' prahu came within the circle of firelight a swarthy Malay approached the fire, dragging a white girl roughly by the arm. No more was needed to convince Number Thirteen of the identity of the party. With a low command to his fellows he urged them to redoubled speed. At the same instant a Dyak warrior caught sight of the approaching boat as it sped into the full glare of the light.

At sight of the occupants the head hunters scattered for their own prahus. The frightful aspect of the enemy turned their savage hearts to water, leaving no fight in their ordinarily warlike souls.

So quickly they moved that as the pursuing prahu touched the bank all the nearer boats had been launched, and the remaining pirates were scurrying across the little island for those which lay upon the opposite side. Among these was the Malay who guarded the girl, but he had not been quick enough to prevent Virginia Maxon recognizing the stalwart figure standing in the bow of the oncoming craft.

As he dragged her away toward the prahu of Muda Saffir she cried out to the strange white man who seemed her self-appointed protector.

"Help! Help!" she called. "This way! Across the island!" And then the brown hand of her jailer closed over her mouth. Like a tigress she fought to free herself, or to detain her captor until the rescue party should catch up with them, but the scoundrel was muscled like a bull, and when the girl held back he lifted her across his shoulder and broke into a run.

Rajah Muda Saffir had no stomach for a fight himself, but he was loathe to lose the prize he had but just won, and seeing that his men were panic-stricken he saw no alternative but to rally them for a brief stand that would give the little moment required to slip away in his own prahu with the girl.

Calling aloud for those around him to come to his support he halted fifty yards from his boat just as Number Thirteen with his fierce, brainless horde swept up from the opposite side of the island in the wake of him who bore Virginia Maxon. The old rajah succeeded in gathering some fifty warriors about him from the crews of the two boats which lay near his. His own men he hastened to their posts in his prahu that they might be ready to pull swiftly away the moment that he and the captive were aboard.

The Dyak warriors presented an awe inspiring spectacle in the fitful light of the nearby camp fire. The ferocity of their fierce faces was accentuated by the upturned, bristling tiger cat's teeth which protruded from every ear; while the long feathers of the Argus pheasant waving from their war-caps, the brilliant colors of their war-coats trimmed with the black and white feathers of the hornbill, and the strange devices upon their gaudy shields but added to the savagery of their appearance as they danced and howled, menacing and intimidating, in the path of the charging foe.

A single backward glance was all that Virginia Maxon found it possible to throw in the direction of the rescue party, and in that she saw a sight that lived forever in her memory. At the head of his hideous, misshapen pack sprang the stalwart young giant straight into the heart of the flashing parangs of the howling savages. To right and left fell the mighty bull whip cutting down men with all the force and dispatch of a steel saber. The Dyaks, encouraged by the presence of Muda Saffir in their rear, held their ground; and the infuriated, brainless things that followed the wielder of the bull whip threw themselves upon the head hunters with beating hands and rending fangs.

Number Ten wrested a parang from an adversary, and acting upon his example the other creatures were not long in arming themselves in a similar manner. Cutting and jabbing they hewed their way through the solid ranks of the enemy, until Muda Saffir, seeing that defeat was inevitable turned and fled toward his prahu.

Four of his creatures lay dead as the last of the Dyaks turned to escape from the mad white man who faced naked steel with only a rawhide whip. In panic the head hunters made a wild dash for the two remaining prahus, for Muda Saffir had succeeded in getting away from the island in safety.

Number Thirteen reached the water's edge but a moment after the prow of the rajah's craft had cleared the shore and was swinging up stream under the vigorous strokes of its fifty oarsmen. For an instant he stood poised upon the bank as though to spring after the retreating prahu, but the knowledge that he could not swim held him back--it was useless to throw away his life when the need of it was so great if Virginia Maxon was to be saved.

Turning to the other prahus he saw that one was already launched, but that the crew of the other was engaged in a desperate battle with the seven remaining members of his crew for possession of the boat. Leaping among the combatants he urged his fellows aboard the prahu which was already half filled with Dyaks. Then he shoved the boat out into the river, jumping aboard himself as its prow cleared the gravelly beach.

For several minutes that long, hollowed log was a veritable floating hell of savage, screaming men locked in deadly battle. The sharp parangs of the head hunters were no match for the superhuman muscles of the creatures that battered them about; now lifting one high above his fellows and using the body as a club to beat down those nearby; again snapping an arm or leg as one might break a pipe stem; or hurling a living antagonist headlong above the heads of his fellows to the dark waters of the river. And above them all in the thickest of the fight, towering even above his own giants, rose the mighty figure of the terrible white man, whose very presence wrought havoc with the valor of the brown warriors.

Two more of Number Thirteen's creatures had been cut down in the prahu, but the loss among the Dyaks had been infinitely greater, and to it was now added the desertions of the terror stricken savages who seemed to fear the frightful countenances of their adversaries even as much as they did their prowess.

There remained but a handful of brown warriors in one end of the boat when the advantage of utilizing their knowledge of the river and of navigation occurred to Number Thirteen. Calling to his men he commanded them to cease killing, making prisoners of those who remained instead. So accustomed had his pack now become to receiving and acting upon his orders that they changed their tactics immediately, and one by one the remaining Dyaks were overpowered, disarmed and held.

With difficulty Number Thirteen communicated with them, for among them there was but a single warrior who had ever had intercourse with an Englishman, but at last by means of signs and the few words that were common to them both he made the native understand that he would spare the lives of himself and his companions if they would help him in pursuit of Muda Saffir and the girl.

The Dyaks felt but little loyalty for the rascally Malay they served, since in common with all their kind they and theirs had suffered for generations at the hands of the cruel, crafty and unscrupulous race that had usurped the administration of their land. So it was not difficult to secure from them the promise of assistance in return for their lives.

Number Thirteen noticed that when they addressed him it was always as Bulan, and upon questioning them he discovered that they had given him this title of honor partly in view of his wonderful fighting ability and partly because the sight of his white face emerging from out of the darkness of the river into the firelight of their blazing camp fire had carried to their impressionable minds a suggestion of the tropic moon which they admired and reverenced. Both the name and the idea appealed to Number Thirteen and from that time he adopted Bulan as his rightful cognomen.

The loss of time resulting from the fight in the prahu and the ensuing peace parley permitted Muda Saffir to put considerable distance between himself and his pursuers. The Malay's boat was now alone, for of the eight prahus that remained of the original fleet it was the only one which had taken this branch of the river, the others having scurried into a smaller southerly arm after the fight upon the island, that they might the more easily escape their hideous foemen.

Only Barunda, the headman, knew which channel Rajah Muda Saffir intended following, and Muda wondered why it was that the two boats that were to have borne Barunda's men did not catch up with his. While he had left Barunda and his warriors engaged in battle with the strangers he did not for an instant imagine that they would suffer any severe loss, and that one of their boats should be captured was beyond belief. But this was precisely what had happened, and the second boat, seeing the direction taken by the enemy, had turned down stream the more surely to escape them.

So it was that while Rajah Muda Saffir moved leisurely up the river toward his distant stronghold waiting for the other boats of his fleet to overtake him, Barunda, the headman, guided the white enemy swiftly after him. Barunda had discovered that it was the girl alone this white man wanted. Evidently he either knew nothing of the treasure chest lying in the bottom of Muda Saffir's boat, or, knowing, was indifferent. In either event Barunda thought that he saw a chance to possess himself of the rich contents of the heavy box, and so served his new master with much greater enthusiasm than he had the old.

Beneath the paddles of the natives and the five remaining members of his pack Bulan sped up the dark river after the single prahu with its priceless freight. Already six of the creatures of Professor Maxon's experiments had given up their lives in the service of his daughter, and the remaining six were pushing forward through the inky blackness of the jungle night into the untracked heart of savage Borneo to rescue her from her abductors though they sacrificed their own lives in the endeavor.

Far ahead of them in the bottom of the great prahu crouched the girl they sought. Her thoughts were of the man she felt intuitively to possess the strength, endurance and ability to overcome every obstacle and reach her at last. Would he come in time? Ah, that was the question. The mystery of the stranger appealed to her. A thousand times she had attempted to solve the question of his first appearance on the island at the very moment that his mighty muscles were needed to rescue her from the horrible creature of her father's creation. Then there was his unaccountable disappearance for weeks; there was von Horn's strange reticence and seeming ignorance as to the circumstances which brought the young man to the island, or his equally unaccountable disappearance after having rescued her from Number One. And now, when she suddenly found herself in need of protection, here was the same young man turning up in a most miraculous fashion, and at the head of the terrible creatures of the inner campong.

The riddle was too deep for her--she could not solve it; and then her thoughts were interrupted by the thin, brown hand of Rajah Muda Saffir as it encircled her waist and drew her toward him. Upon the evil lips were hot words of passion. The girl wrenched herself from the man's embrace, and, with a little scream of terror, sprang to her feet, and as Muda Saffir arose to grasp her again she struck him full in the face with one small, clenched fist.

Directly behind the Malay lay the heavy chest of Professor Maxon. As the man stepped backward to recover his equilibrium both feet struck the obstacle. For an instant he tottered with wildly waving arms in an endeavor to regain his lost balance, then, with a curse upon his lips, he lunged across the box and over the side of the prahu into the dark waters of the river.