In so far as I could know I reached my apartment without detection. Hiding my rope where I was sure it would not be discovered, I sought my sleeping silks and furs and was soon asleep.

The following morning as I emerged from my quarters I caught a fleeting glimpse of a figure in a nearby corridor and from then on for a long time I had further evidence that Ras Thavas suspicioned me. I went at once to his quarters, as had been my habit. He seemed restless, but he gave me no hint that he held any assurance that I had been responsible for the disappearance of Valla Dia, and I think that he was far from positive of it. It was simply that his judgment pointed to the fact that I was the only person who might have any reason for interfering in any way with this particular subject, and he was having me watched to either prove or disprove the truth of his reasonable suspicions. His restlessness he explained to me himself.

"I have often studied the reaction of others who have undergone brain transference," he said, "and so I am not wholly surprised at my own. Not only has my brain energy been stimulated, resulting in an increased production of nervous energy, but I also feel the effects of the young tissue and youthful blood of my new body. They are affecting my consciousness in a way that my experiment had vaguely indicated, but which I now see must be actually experienced to be fully understood. My thoughts, my inclinations, even my ambitions have been changed, or at least coloured, by the transfer. It will take some time for me to find myself."

Though uninterested, I listened politely until he was through and then I changed the subject "Have you located the missing woman?" I asked.

He shook his head, negatively.

"You must appreciate, Ras Thavas," I said, "that I fully realize that you must have known that the removal or destruction of that woman would entirely frustrate my entire plan. You are master here. Nothing that passes is without your knowledge."

"You mean that I am responsible for the disappearance of the woman?" he demanded.

"Certainly. It is obvious. I demand that she be restored."

He lost his temper. "Who are you to demand?" he shouted. "You are naught but a slave. Cease your impudence or I shall erase you--erase you. It will be as though you never had existed."

I laughed in his face. "Anger is the most futile attribute of the sentimentalist," I reminded him. "You will not erase me, for I alone stand between you and mortality."

"I can train another," he parried.

"But you could not trust him," I pointed out.

"But you bargained with me for my life when you had me in your power," he cried.

"For nothing that it would have harmed you to have granted willingly. I did not ask anything for myself. Be that as it may, you will trust me again. You will trust, for no other reason than that you will be forced to trust me. So why not win my gratitude and my loyalty by returning the woman to me and carrying out in spirit as well as in fact the terms of our agreement?"

He turned and looked steadily at me. "Vad Varo," he said, "I give you the word of honor of a Barsoomian noble that I know absolutely nothing concerning the whereabouts of 4296-E-2631-H."

"Perhaps Yamdor does," I persisted.

"Nor Yamdor. Of my knowledge no person in any way connected with me knows what became of it. I have spoken the truth."

Well, the conversation was not as profitless as it might appear, for I was sure that it had almost convinced Ras Thavas that I was equally as ignorant of the fate of Valla Dia as was he. That it had not wholly convinced him was evidenced by the fact that the espionage continued for a long time, a fact which determined me to use Ras Thavas' own methods in my own defence. I had had allotted to me a number of slaves, and these I had won over by kindness and understanding until I knew that I had the full measure of their loyalty. They had no reason to love Ras Thavas and every reason to hate him; on the other hand they had no reason to hate me, and I saw to it that they had every reason to love me.

The result was that I had no difficulty in enlisting the services of a couple of them to spy upon Ras Thavas' spies, with the result that I was soon apprised that my suspicions were well founded--I was being constantly watched every minute that I was out of my apartments, but the spying did not come beyond my outer chamber walls. That was why I had been successful in reaching the vault in the manner that I had, the spies having assumed that I would leave my chamber only by its natural exit, had been content to guard that and permit my windows to go unwatched.

I think it was about two of our months that the spying continued and then my men reported that it seemed to have ceased entirely. All that time I was fretting at the delay, for I wanted to be about my plans which would have been absolutely impossible for me to carry out if I were being watched. I had spent the interval in studying the geography of the north-eastern Barsoomian hemisphere where my activities were to be carried on, and also in scanning a great number of case histories and inspecting the subjects to which they referred; but at last, with the removal of the spies, it began to look as though I might soon commence to put my plans in active operation.

Ras Thavas had for some time permitted me considerable freedom in independent investigation and experiment, and this I determined to take advantage of in every possible way that might forward my plans for the resurrection of Valla Dia. My study of the histories of many of the cases had been with the possibility in mind of discovering subjects that might be of assistance to me in my venture. Among those that had occupied my careful attention were, quite naturally, the cases with which I had been most familiar, namely: 378-J-493811-P, the red-man from whose vicious attack I had saved Ras Thavas upon the day of my advent upon Mars; and he whose brain had been divided with an ape.

The former, 378-J-493811-P, had been a native of Phundahl--a young warrior attached to the court of Xaxa, Jeddara of Phundahl--and a victim of assassination. His body had been purchased by a Phundahlian noble for the purpose, as Ras Thavas had narrated, of winning the favor of a young beauty. I felt that I might possibly enlist his services, but that would depend upon the extent of his loyalty towards Xaxa, which I could only determine by reviving and questioning him.

He whose brain had been divided with an ape had originated in Ptarth, which lay at a considerable distance to the west of Phundahl and a little south and about an equal distance from Duhor, which lay north and a little west of it. An inhabitant of Ptarth, I reasoned, would know much of the entire country included in the triangle formed by Phundahl, Ptarth and Duhor; the strength and ferocity of the great ape would prove of value in crossing beast-infested wastes; and I felt that I could hold forth sufficient promise to the human half of the great beast's brain, which really now dominated the creature, to win its support and loyalty. The third subject that I had tentatively selected had been a notorious Toonolian assassin, whose audacity, fearlessness and swordsmanship had won for him a reputation that had spread far beyond the boundaries of his country.

Ras Thavas, himself a Toonolian, had given me something of the history of this man whose grim calling is not without honor upon Barsoom, and which Gor Hajus had raised still higher in the esteem of his countrymen through the fact that he never struck down a woman or a good man and that he never struck from behind.

His killings were always the results of fair fights in which the victim had every opportunity to defend himself and slay his attacker; and he was famous for his loyalty to his friends. In fact this very loyalty had been a contributing factor in his downfall which had brought him to one of Ras Thavas' ersite slabs some years since, for he had earned the enmity of Vobis Kan, Jeddak of Toonol, through his refusal to assassinate a man who once had befriended Gor Hajus in some slight degree; following which Vobis Kan conceived the suspicion that Gor Hajus had him marked for slaying. The result was inevitable: Gor Hajus was arrested and condemned to death; immediately following the execution of the sentence, an agent of Ras Thavas had purchased the body.

These three, then, I had chosen to be my partners in my great adventure. It is true that I had not discussed the matter with any one of them, but my judgment assured me that I would have no difficulty in enlisting their services and loyalty in return for their total resurrection.

My first task lay in renewing the organs of 378-J-493811-P and of Gor Hajus, which had been injured by the wounds that had laid them low; the former requiring a new lung and the latter a new heart, his executioner having run him through with a short-sword. I hesitated to ask Ras Thavas' permission to experiment on these subjects for fear of the possibility of arousing his suspicions, in which event he would probably have them destroyed, and so I was forced to accomplish my designs by subterfuge and stealth. To this end I made it a practice for weeks to carry my regular laboratory work far into the night, often requiring the services of various assistants that all might become accustomed to the sight of me at work at unusual hours. In my selection of these assistants I made it a point to choose two of the very spies that Ras Thavas had set to watching me. While it was true that they were no longer employed in this particular service, I had hopes that they would carry word of my activities to their master; and I was careful to see that they received from me the proper suggestions that would mould their report in language far from harmful to me. By the merest suggestion I carried to them the idea that I worked thus late purely for the love of the work itself and the tremendous interest in it that Ras Thavas had awakened within my mind. Some nights I worked with assistants and as often I did not, but always I was careful to assure myself that the following morning those in the office were made aware that I had labored far into the preceding night.

This groundwork carefully prepared, I had comparatively little fear of the results of actual discovery when I set to work upon the warrior of Phundahl and the assassin of Toonol. I chose the former first. His lung was badly injured where my blade had passed through it, but from the laboratory where were kept fractional bodies I brought a perfect lung, with which I replaced the one that I had ruined. The work occupied but half the night. So anxious was I to complete my task that I immediately opened up the breast of Gor Hajus, for whom I had selected an unusually strong and powerful heart and by working rapidly I succeeded in completing the transference before dawn. Having known the nature of the wounds that had dispatched these two men, I had spent weeks in performing similar operations that I might perfect myself especially in this work; and having encountered no unusual pathological conditions in either subject, the work had progressed smoothly and with great rapidity. I had completed what I had feared would be the most difficult part of my task and now, having removed as far as possible all signs of the operation except the therapeutic tape which closed the incisions, I returned to my quarters for a few minutes of much-needed rest, praying that Ras Thavas would not by any chance examine either of the subjects upon which I had been working, although I had fortified myself against such a contingency by entering full details of the operation upon the history card of each subject that, in the event of discovery, any suspicion of ulterior motives upon my part might be allayed by my play of open frankness.

I arose at the usual time and went at once to Ras Thavas' apartment, where I was met with a bombshell that nearly wrecked my composure. He eyed me closely for a long minute before he spoke.

"You worked late last night, Vad Varo," he said.

"I often do," I replied, lightly; but my heart was heavy as a stone.

"And what might it have been that so occupied your interest?" he inquired.

I felt as a mouse with which the cat is playing. "I have been doing quite a little lung and heart transference of late," I replied, "and I became so engrossed with my work that I did not note the passage of time."

"I have known that you worked late at night. Do you think it wise?"

At that moment I felt that it had been very unwise, yet I assured him to the contrary.

"I was restless," he said. "I could not sleep and so I went to your quarters after midnight, but you were not there. I wanted someone with whom to talk, but your slaves knew only that you were not there--where you were they did not know--so I set out to search for you." My heart went into my sandals. "I guessed that you were in one of the laboratories, but though I visited several I did not find you." My heart arose with the lightness of a feather. "Since my own transference I have been cursed with restlessness and sleeplessness, so that I could almost wish for the return of my old corpse--the youth of my body harmonizes not with the antiquity of my brain. It is filled with latent urges and desires that comport illy with the serious subject matter of my mind."

"What your body needs," I said, "is exercise. It is young, strong, virile. Work it hard and it will let your brain rest at night."

"I know that you are right," he replied. "I have reached that same conclusion myself. In fact, not finding you, I walked in the gardens for an hour or more before returning to my quarters, and then I slept soundly. I shall walk every night when I cannot sleep, or I shall go into the laboratories and work as do you."

This news was most disquieting. Now I could never be sure but that Ras Thavas was wandering about at night and I had one more very important night's work to do, perhaps two. The only way that I could be sure of him was to be with him.

"Send for me when you are restless," I said, "and I will walk and work with you. You should not go about thus at night alone."

"Very well," he said, "I may do that occasionally."

I hoped that he would do it always, for then I would know that when he failed to send for me he was safe in his own quarters. Yet I saw that I must henceforth face the menace of detection; and knowing this I determined to hasten the completion of my plans and to risk everything on a single bold stroke.

That night I had no opportunity to put it into action as Ras Thavas sent for me early and informed me that we would walk in the gardens until he was tired. Now, as I needed a full night for what I had in mind and as Ras Thavas walked until midnight, I was compelled to forego everything for that evening, but the following morning I persuaded him to walk early on the pretext that I should like to go beyond the enclosure and see something of Barsoom besides the inside of his laboratories and his gardens. I had little confidence that he would grant my request, yet he did so. I am sure he never would have done it had he possessed his old body; but thus greatly had young blood changed Ras Thavas.

I had never been beyond the buildings, nor had I seen beyond, since there were no windows in the outside walls of any of the structures and upon the garden side the trees had grown to such a height that they obstructed all view beyond them. For a time we walked in another garden just inside the outer wall, and then I asked Ras Thavas if I might go even beyond this.

"No," he said. "It would not be safe."

"And why not?" I asked.

"I will show you and at the same time give you a much broader view of the outside world than you could obtain by merely passing through the gate. Come, follow me!" He led me immediately to a lofty tower that rose at the corner of the largest building of the group that comprised his vast establishment. Within was a circular runway which led not only upward, but down as well. This we ascended, passing openings at each floor, until we came at last out upon its lofty summit.

About me spread the first Barsoomian landscape of any extent upon which my eyes had yet rested during the long months that I had spent upon the Red Planet. For almost an Earthly year I had been immured within the grim walls of Ras Thavas' bloody laboratory, until, such creatures of habit are we, the weird life there had grown to seem quite natural and ordinary; but with this first glimpse of open country there surged up within me an urge for freedom, for space, for room to move about, such as I knew would not be long denied.

Directly beneath lay an irregular patch of rocky land elevated perhaps a dozen feet or more above the general level of the immediately surrounding country. Its extent was, at a rough guess, a hundred acres. Upon this stood the buildings and grounds, which were enclosed in a high wall. The tower upon which we stood was situated at about the centre of the total area enclosed. Beyond the outer wall was a strip of rocky ground on which grew a sparse forest of fair sized trees interspersed with patches of a jungle growth, and beyond all, what appeared to be an oozy marsh through which were narrow water courses connecting occasional open water--little lakes, the largest of which could have comprised scarce two acres. This landscape extended as far as the eye could reach, broken by occasional islands similar to that upon which we were and at a short distance by the skyline of a large city, whose towers and domes and minarets glistened and sparkled in the sun as though plated with shining metals and picked out with precious gems.

This, I knew, must be Toonol and all about us the Great Toonolian Marshes which extend nearly eighteen hundred Earth miles east and west and in some places have a width of three hundred miles. Little is known about them in other portions of Barsoom as they are frequented by fierce beasts, afford no landing places for fliers and are commanded by Phundahl at their western end and Toonol at the east, inhospitable kingdoms that invite no intercourse with the outside world and maintain their independence alone by their inaccessibility and savage aloofness.

As my eyes returned to the island at our feet I saw a huge form emerge from one of the nearby patches of jungle a short distance beyond the outer wall. It was followed by a second and a third. Ras Thavas saw that the creatures had attracted my notice.

"There," he said, pointing to them, "are three of a number of similar reasons why it would not have been safe for us to venture outside the enclosure."

They were great white apes of Barsoom, creatures so savage that even that fierce Barsoomian lion, the banth, hesitates to cross their path.

"They serve two purposes," explained Ras Thavas. "They discourage those who might otherwise creep upon me by night from the city of Toonol, where I am not without many good enemies, and they prevent desertion upon the part of my slaves and assistants."

"But how do your clients reach you?" I asked. "How are your supplies brought in?"

He tuned and pointed down toward the highest portion of the irregular roof of the building below us. Built upon it was a large, shed-like structure. "There," he said, "I keep three small ships. One of them goes every day to Toonol."

I was overcome with eagerness to know more about these ships, in which I thought I saw a much needed means of escape from the island; but I dared not question him for fear of arousing his suspicions.

As we turned to descend the tower runway I expressed interest in the structure which gave evidence of being far older than any of the surrounding buildings.

"This tower," said Ras Thavas, "was built some twenty-three thousand years ago by an ancestor of mine who was driven from Toonol by the reigning Jeddak of the time. Here, and upon other islands, he gathered a considerable following, dominated the surrounding marshes and defended himself successfully for hundreds of years. While my family has been permitted to return to Toonol since, this has been their home; to which, one by one, have been added the various buildings which you see about the tower, each floor of which connects with the adjacent building from the roof to the lowest pits beneath the ground."

This information also interested me greatly since I thought that I saw where it too might have considerable bearing upon my plan of escape, and so, as we descended the runway, I encouraged Ras Thavas to discourse upon the construction of the tower, its relation to the other buildings and especially its accessibility from the pits. We walked again in the outer garden and by the time we returned to Ras Thavas' quarters it was almost dark and the master surgeon was considerably fatigued.

"I feel that I shall sleep well to-night," he said as I left him.

"I hope so, Ras Thavas," I replied.