Leaping from roof to roof, I soon reached an open window in the building where I hoped to find the Heliumite, and in another moment I stood in the room before him. He was alone and showed no surprise at my coming, saying he had expected me much earlier, as my tour of duty must have ended some time since.

I saw that he knew nothing of the events of the day at the palace, and when I had enlightened him he was all excitement. The news that Dejah Thoris had promised her hand to Sab Than filled him with dismay.

"It cannot be," he exclaimed. "It is impossible! Why no man in all Helium but would prefer death to the selling of our loved princess to the ruling house of Zodanga. She must have lost her mind to have assented to such an atrocious bargain. You, who do not know how we of Helium love the members of our ruling house, cannot appreciate the horror with which I contemplate such an unholy alliance."

"What can be done, John Carter?" he continued. "You are a resourceful man. Can you not think of some way to save Helium from this disgrace?"

"If I can come within sword's reach of Sab Than," I answered, "I can solve the difficulty in so far as Helium is concerned, but for personal reasons I would prefer that another struck the blow that frees Dejah Thoris."

Kantos Kan eyed me narrowly before he spoke.

"You love her!" he said. "Does she know it?"

"She knows it, Kantos Kan, and repulses me only because she is promised to Sab Than."

The splendid fellow sprang to his feet, and grasping me by the shoulder raised his sword on high, exclaiming:

"And had the choice been left to me I could not have chosen a more fitting mate for the first princess of Barsoom. Here is my hand upon your shoulder, John Carter, and my word that Sab Than shall go out at the point of my sword for the sake of my love for Helium, for Dejah Thoris, and for you. This very night I shall try to reach his quarters in the palace."

"How?" I asked. "You are strongly guarded and a quadruple force patrols the sky."

He bent his head in thought a moment, then raised it with an air of confidence.

"I only need to pass these guards and I can do it," he said at last. "I know a secret entrance to the palace through the pinnacle of the highest tower. I fell upon it by chance one day as I was passing above the palace on patrol duty. In this work it is required that we investigate any unusual occurrence we may witness, and a face peering from the pinnacle of the high tower of the palace was, to me, most unusual. I therefore drew near and discovered that the possessor of the peering face was none other than Sab Than. He was slightly put out at being detected and commanded me to keep the matter to myself, explaining that the passage from the tower led directly to his apartments, and was known only to him. If I can reach the roof of the barracks and get my machine I can be in Sab Than's quarters in five minutes; but how am I to escape from this building, guarded as you say it is?"

"How well are the machine sheds at the barracks guarded?" I asked.

"There is usually but one man on duty there at night upon the roof."

"Go to the roof of this building, Kantos Kan, and wait me there."

Without stopping to explain my plans I retraced my way to the street and hastened to the barracks. I did not dare to enter the building, filled as it was with members of the air-scout squadron, who, in common with all Zodanga, were on the lookout for me.

The building was an enormous one, rearing its lofty head fully a thousand feet into the air. But few buildings in Zodanga were higher than these barracks, though several topped it by a few hundred feet; the docks of the great battleships of the line standing some fifteen hundred feet from the ground, while the freight and passenger stations of the merchant squadrons rose nearly as high.

It was a long climb up the face of the building, and one fraught with much danger, but there was no other way, and so I essayed the task. The fact that Barsoomian architecture is extremely ornate made the feat much simpler than I had anticipated, since I found ornamental ledges and projections which fairly formed a perfect ladder for me all the way to the eaves of the building. Here I met my first real obstacle. The eaves projected nearly twenty feet from the wall to which I clung, and though I encircled the great building I could find no opening through them.

The top floor was alight, and filled with soldiers engaged in the pastimes of their kind; I could not, therefore, reach the roof through the building.

There was one slight, desperate chance, and that I decided I must take--it was for Dejah Thoris, and no man has lived who would not risk a thousand deaths for such as she.

Clinging to the wall with my feet and one hand, I unloosened one of the long leather straps of my trappings at the end of which dangled a great hook by which air sailors are hung to the sides and bottoms of their craft for various purposes of repair, and by means of which landing parties are lowered to the ground from the battleships.

I swung this hook cautiously to the roof several times before it finally found lodgment; gently I pulled on it to strengthen its hold, but whether it would bear the weight of my body I did not know. It might be barely caught upon the very outer verge of the roof, so that as my body swung out at the end of the strap it would slip off and launch me to the pavement a thousand feet below.

An instant I hesitated, and then, releasing my grasp upon the supporting ornament, I swung out into space at the end of the strap. Far below me lay the brilliantly lighted streets, the hard pavements, and death. There was a little jerk at the top of the supporting eaves, and a nasty slipping, grating sound which turned me cold with apprehension; then the hook caught and I was safe.

Clambering quickly aloft I grasped the edge of the eaves and drew myself to the surface of the roof above. As I gained my feet I was confronted by the sentry on duty, into the muzzle of whose revolver I found myself looking.

"Who are you and whence came you?" he cried.

"I am an air scout, friend, and very near a dead one, for just by the merest chance I escaped falling to the avenue below," I replied.

"But how came you upon the roof, man? No one has landed or come up from the building for the past hour. Quick, explain yourself, or I call the guard."

"Look you here, sentry, and you shall see how I came and how close a shave I had to not coming at all," I answered, turning toward the edge of the roof, where, twenty feet below, at the end of my strap, hung all my weapons.

The fellow, acting on impulse of curiosity, stepped to my side and to his undoing, for as he leaned to peer over the eaves I grasped him by his throat and his pistol arm and threw him heavily to the roof. The weapon dropped from his grasp, and my fingers choked off his attempted cry for assistance. I gagged and bound him and then hung him over the edge of the roof as I myself had hung a few moments before. I knew it would be morning before he would be discovered, and I needed all the time that I could gain.

Donning my trappings and weapons I hastened to the sheds, and soon had out both my machine and Kantos Kan's. Making his fast behind mine I started my engine, and skimming over the edge of the roof I dove down into the streets of the city far below the plane usually occupied by the air patrol. In less than a minute I was settling safely upon the roof of our apartment beside the astonished Kantos Kan.

I lost no time in explanation, but plunged immediately into a discussion of our plans for the immediate future. It was decided that I was to try to make Helium while Kantos Kan was to enter the palace and dispatch Sab Than. If successful he was then to follow me. He set my compass for me, a clever little device which will remain steadfastly fixed upon any given point on the surface of Barsoom, and bidding each other farewell we rose together and sped in the direction of the palace which lay in the route which I must take to reach Helium.

As we neared the high tower a patrol shot down from above, throwing its piercing searchlight full upon my craft, and a voice roared out a command to halt, following with a shot as I paid no attention to his hail. Kantos Kan dropped quickly into the darkness, while I rose steadily and at terrific speed raced through the Martian sky followed by a dozen of the air-scout craft which had joined the pursuit, and later by a swift cruiser carrying a hundred men and a battery of rapid-fire guns. By twisting and turning my little machine, now rising and now falling, I managed to elude their search- lights most of the time, but I was also losing ground by these tactics, and so I decided to hazard everything on a straight- away course and leave the result to fate and the speed of my machine.

Kantos Kan had shown me a trick of gearing, which is known only to the navy of Helium, that greatly increased the speed of our machines, so that I felt sure I could distance my pursuers if I could dodge their projectiles for a few moments.

As I sped through the air the screeching of the bullets around me convinced me that only by a miracle could I escape, but the die was cast, and throwing on full speed I raced a straight course toward Helium. Gradually I left my pursuers further and further behind, and I was just congratulating myself on my lucky escape, when a well-directed shot from the cruiser exploded at the prow of my little craft. The concussion nearly capsized her, and with a sickening plunge she hurtled downward through the dark night.

How far I fell before I regained control of the plane I do not know, but I must have been very close to the ground when I started to rise again, as I plainly heard the squealing of animals below me. Rising again I scanned the heavens for my pursuers, and finally making out their lights far behind me, saw that they were landing, evidently in search of me.

Not until their lights were no longer discernible did I venture to flash my little lamp upon my compass, and then I found to my consternation that a fragment of the projectile had utterly destroyed my only guide, as well as my speedometer. It was true I could follow the stars in the general direction of Helium, but without knowing the exact location of the city or the speed at which I was traveling my chances for finding it were slim.

Helium lies a thousand miles southwest of Zodanga, and with my compass intact I should have made the trip, barring accidents, in between four and five hours. As it turned out, however, morning found me speeding over a vast expanse of dead sea bottom after nearly six hours of continuous flight at high speed. Presently a great city showed below me, but it was not Helium, as that alone of all Barsoomian metropolises consists in two immense circular walled cities about seventy-five miles apart and would have been easily distinguishable from the altitude at which I was flying.

Believing that I had come too far to the north and west, I turned back in a southeasterly direction, passing during the forenoon several other large cities, but none resembling the description which Kantos Kan had given me of Helium. In addition to the twin-city formation of Helium, another distinguishing feature is the two immense towers, one of vivid scarlet rising nearly a mile into the air from the center of one of the cities, while the other, of bright yellow and of the same height, marks her sister.