As the ruler of Ptarth, followed by his courtiers, descended from the landing-stage above the palace, the servants dropped into their places in the rear of their royal or noble masters, and behind the others one lingered to the last. Then quickly stooping he snatched the sandal from his right foot, slipping it into his pocket-pouch.

When the party had come to the lower levels, and the jeddak had dispersed them by a sign, none noticed that the forward fellow who had drawn so much attention to himself before the Prince of Helium departed, was no longer among the other servants.

To whose retinue he had been attached none had thought to inquire, for the followers of a Martian noble are many, coming and going at the whim of their master, so that a new face is scarcely ever questioned, as the fact that a man has passed within the palace walls is considered proof positive that his loyalty to the jeddak is beyond question, so rigid is the examination of each who seeks service with the nobles of the court.

A good rule that, and only relaxed by courtesy in favour of the retinue of visiting royalty from a friendly foreign power.

It was late in the morning of the next day that a giant serving man in the harness of the house of a great Ptarth noble passed out into the city from the palace gates. Along one broad avenue and then another he strode briskly until he had passed beyond the district of the nobles and had come to the place of shops. Here he sought a pretentious building that rose spire-like toward the heavens, its outer walls elaborately wrought with delicate carvings and intricate mosaics.

It was the Palace of Peace in which were housed the representatives of the foreign powers, or rather in which were located their embassies; for the ministers themselves dwelt in gorgeous palaces within the district occupied by the nobles.

Here the man sought the embassy of Dusar. A clerk arose questioningly as he entered, and at his request to have a word with the minister asked his credentials. The visitor slipped a plain metal armlet from above his elbow, and pointing to an inscription upon its inner surface, whispered a word or two to the clerk.

The latter's eyes went wide, and his attitude turned at once to one of deference. He bowed the stranger to a seat, and hastened to an inner room with the armlet in his hand. A moment later he reappeared and conducted the caller into the presence of the minister.

For a long time the two were closeted together, and when at last the giant serving man emerged from the inner office his expression was cast in a smile of sinister satisfaction. From the Palace of Peace he hurried directly to the palace of the Dusarian minister.

That night two swift fliers left the same palace top. One sped its rapid course toward Helium; the other —

Thuvia of Ptarth strolled in the gardens of her father's palace, as was her nightly custom before retiring. Her silks and furs were drawn about her, for the air of Mars is chill after the sun has taken his quick plunge beneath the planet's western verge.

The girl's thoughts wandered from her impending nuptials, that would make her empress of Kaol, to the person of the trim young Heliumite who had laid his heart at her feet the preceding day.

Whether it was pity or regret that saddened her expression as she gazed toward the southern heavens where she had watched the lights of his flier disappear the previous night, it would be difficult to say.

So, too, is it impossible to conjecture just what her emotions may have been as she discerned the lights of a flier speeding rapidly out of the distance from that very direction, as though impelled toward her garden by the very intensity of the princess' thoughts.

She saw it circle lower above the palace until she was positive that it but hovered in preparation for a landing.

Presently the powerful rays of its searchlight shot downward from the bow. They fell upon the landing-stage for a brief instant, revealing the figures of the Ptarthian guard, picking into brilliant points of fire the gems upon their gorgeous harnesses.

Then the blazing eye swept onward across the burnished domes and graceful minarets, down into court and park and garden to pause at last upon the ersite bench and the girl standing there beside it, her face upturned full toward the flier.

For but an instant the searchlight halted upon Thuvia of Ptarth, then it was extinguished as suddenly as it had come to life. The flier passed on above her to disappear beyond a grove of lofty skeel trees that grew within the palace grounds.

The girl stood for some time as it had left her, except that her head was bent and her eyes downcast in thought.

Who but Carthoris could it have been? She tried to feel anger that he should have returned thus, spying upon her; but she found it difficult to be angry with the young prince of Helium.

What mad caprice could have induced him so to transgress the etiquette of nations? For lesser things great powers had gone to war.

The princess in her was shocked and angered — but what of the girl!

And the guard — what of them? Evidently they, too, had been so much surprised by the unprecedented action of the stranger that they had not even challenged; but that they had no thought to let the thing go unnoticed was quickly evidenced by the skirring of motors upon the landing-stage and the quick shooting airward of a long-lined patrol boat.

Thuvia watched it dart swiftly eastward. So, too, did other eyes watch.

Within the dense shadows of the skeel grove, in a wide avenue beneath o'erspreading foliage, a flier hung a dozen feet above the ground. From its deck keen eyes watched the far-fanning searchlight of the patrol boat. No light shone from the enshadowed craft. Upon its deck was the silence of the tomb. Its crew of a half-dozen red warriors watched the lights of the patrol boat diminishing in the distance.

"The intellects of our ancestors are with us to-night," said one in a low tone.

"No plan ever carried better," returned another. "They did precisely as the prince foretold."

He who had first spoken turned toward the man who squatted before the control board.

"Now!" he whispered. There was no other order given. Every man upon the craft had evidently been well schooled in each detail of that night's work. Silently the dark hull crept beneath the cathedral arches of the dark and silent grove.

Thuvia of Ptarth, gazing toward the east, saw the blacker blot against the blackness of the trees as the craft topped the buttressed garden wall. She saw the dim bulk incline gently downward toward the scarlet sward of the garden.

She knew that men came not thus with honourable intent. Yet she did not cry aloud to alarm the near-by guardsmen, nor did she flee to the safety of the palace.

Why?

I can see her shrug her shapely shoulders in reply as she voices the age-old, universal answer of the woman: Because!

Scarce had the flier touched the ground when four men leaped from its deck. They ran forward toward the girl.

Still she made no sign of alarm, standing as though hypnotized. Or could it have been as one who awaited a welcome visitor?

Not until they were quite close to her did she move. Then the nearer moon, rising above the surrounding foliage, touched their faces, lighting all with the brilliancy of her silver rays.

Thuvia of Ptarth saw only strangers — warriors in the harness of Dusar. Now she took fright, but too late!

Before she could voice but a single cry, rough hands seized her. A heavy silken scarf was wound about her head. She was lifted in strong arms and borne to the deck of the flier. There was the sudden whirl of propellers, the rushing of air against her body, and, from far beneath the shouting and the challenge from the guard.

Racing toward the south another flier sped toward Helium. In its cabin a tall red man bent over the soft sole of an upturned sandal. With delicate instruments he measured the faint imprint of a small object which appeared there. Upon a pad beside him was the outline of a key, and here he noted the results of his measurements.

A smile played upon his lips as he completed his task and turned to one who waited at the opposite side of the table.

"The man is a genius," he remarked.

"Only a genius could have evolved such a lock as this is designed to spring. Here, take the sketch, Larok, and give all thine own genius full and unfettered freedom in reproducing it in metal."

The warrior-artificer bowed. "Man builds naught," he said, "that man may not destroy." Then he left the cabin with the sketch.

As dawn broke upon the lofty towers which mark the twin cities of Helium — the scarlet tower of one and the yellow tower of its sister — a flier floated lazily out of the north.

Upon its bow was emblazoned the signia of a lesser noble of a far city of the empire of Helium. Its leisurely approach and the evident confidence with which it moved across the city aroused no suspicion in the minds of the sleepy guard. Their round of duty nearly done, they had little thought beyond the coming of those who were to relieve them.

Peace reigned throughout Helium. Stagnant, emasculating peace. Helium had no enemies. There was naught to fear.

Without haste the nearest air patrol swung sluggishly about and approached the stranger. At easy speaking distance the officer upon her deck hailed the incoming craft.

The cheery "Kaor!" and the plausible explanation that the owner had come from distant parts for a few days of pleasure in gay Helium sufficed. The air-patrol boat sheered off, passing again upon its way. The stranger continued toward a public landing-stage, where she dropped into the ways and came to rest.

At about the same time a warrior entered her cabin.

"It is done, Vas Kor," he said, handing a small metal key to the tall noble who had just risen from his sleeping silks and furs.

"Good!" exclaimed the latter. "You must have worked upon it all during the night, Larok."

The warrior nodded.

"Now fetch me the Heliumetic metal you wrought some days since," commanded Vas Kor.

This done, the warrior assisted his master to replace the handsome jewelled metal of his harness with the plainer ornaments of an ordinary fighting man of Helium, and with the insignia of the same house that appeared upon the bow of the flier.

Vas Kor breakfasted on board. Then he emerged upon the aerial dock, entered an elevator, and was borne quickly to the street below, where he was soon engulfed by the early morning throng of workers hastening to their daily duties.

Among them his warrior trappings were no more remarkable than is a pair of trousers upon Broadway. All Martian men are warriors, save those physically unable to bear arms. The tradesman and his clerk clank with their martial trappings as they pursue their vocations. The schoolboy, coming into the world, as he does, almost adult from the snowy shell that has encompassed his development for five long years, knows so little of life without a sword at his hip that he would feel the same discomfiture at going abroad unarmed that an Earth boy would experience in walking the streets knicker-bockerless.

Vas Kor's destination lay in Greater Helium, which lies some seventy-five miles across the level plain from Lesser Helium. He had landed at the latter city because the air patrol is less suspicious and alert than that above the larger metropolis where lies the palace of the jeddak.

As he moved with the throng in the parklike canyon of the thoroughfare the life of an awakening Martian city was in evidence about him. Houses, raised high upon their slender metal columns for the night were dropping gently toward the ground. Among the flowers upon the scarlet sward which lies about the buildings children were already playing, and comely women laughing and chatting with their neighbours as they culled gorgeous blossoms for the vases within doors.

The pleasant "kaor" of the Barsoomian greeting fell continually upon the ears of the stranger as friends and neighbours took up the duties of a new day.

The district in which he had landed was residential — a district of merchants of the more prosperous sort. Everywhere were evidences of luxury and wealth. Slaves appeared upon every housetop with gorgeous silks and costly furs, laying them in the sun for airing. Jewel-encrusted women lolled even thus early upon the carven balconies before their sleeping apartments. Later in the day they would repair to the roofs when the slaves had arranged couches and pitched silken canopies to shade them from the sun.

Strains of inspiring music broke pleasantly from open windows, for the Martians have solved the problem of attuning the nerves pleasantly to the sudden transition from sleep to waking that proves so difficult a thing for most Earth folk.

Above him raced the long, light passenger fliers, plying, each in its proper plane, between the numerous landing-stages for internal passenger traffic. Landing-stages that tower high into the heavens are for the great international passenger liners. Freighters have other landing-stages at various lower levels, to within a couple of hundred feet of the ground; nor dare any flier rise or drop from one plane to another except in certain restricted districts where horizontal traffic is forbidden.

Along the close-cropped sward which paves the avenue ground fliers were moving in continuous lines in opposite directions. For the greater part they skimmed along the surface of the sward, soaring gracefully into the air at times to pass over a slower-going driver ahead, or at intersections, where the north and south traffic has the right of way and the east and west must rise above it.

From private hangars upon many a roof top fliers were darting into the line of traffic. Gay farewells and parting admonitions mingled with the whirring of motors and the subdued noises of the city.

Yet with all the swift movement and the countless thousands rushing hither and thither, the predominant suggestion was that of luxurious ease and soft noiselessness.

Martians dislike harsh, discordant clamour. The only loud noises they can abide are the martial sounds of war, the clash of arms, the collision of two mighty dreadnoughts of the air. To them there is no sweeter music than this.

At the intersection of two broad avenues Vas Kor descended from the street level to one of the great pneumatic stations of the city. Here he paid before a little wicket the fare to his destination with a couple of the dull, oval coins of Helium.

Beyond the gatekeeper he came to a slowly moving line of what to Earthly eyes would have appeared to be conical-nosed, eight-foot projectiles for some giant gun. In slow procession the things moved in single file along a grooved track. A half dozen attendants assisted passengers to enter, or directed these carriers to their proper destination.

Vas Kor approached one that was empty. Upon its nose was a dial and a pointer. He set the pointer for a certain station in Greater Helium, raised the arched lid of the thing, stepped in and lay down upon the upholstered bottom. An attendant closed the lid, which locked with a little click, and the carrier continued its slow way.

Presently it switched itself automatically to another track, to enter, a moment later, one of the series of dark-mouthed tubes.

The instant that its entire length was within the black aperture it sprang forward with the speed of a rifle ball. There was an instant of whizzing — a soft, though sudden, stop, and slowly the carrier emerged upon another platform, another attendant raised the lid and Vas Kor stepped out at the station beneath the centre of Greater Helium, seventy-five miles from the point at which he had embarked.

Here he sought the street level, stepping immediately into a waiting ground flier. He spoke no word to the slave sitting in the driver's seat. It was evident that he had been expected, and that the fellow had received his instructions before his coming.

Scarcely had Vas Kor taken his seat when the flier went quickly into the fast-moving procession, turning presently from the broad and crowded avenue into a less congested street. Presently it left the thronged district behind to enter a section of small shops, where it stopped before the entrance to one which bore the sign of a dealer in foreign silks.

Vas Kor entered the low-ceiling room. A man at the far end motioned him toward an inner apartment, giving no further sign of recognition until he had passed in after the caller and closed the door.

Then he faced his visitor, saluting deferentially.

"Most noble — " he commenced, but Vas Kor silenced him with a gesture.

"No formalities," he said. "We must forget that I am aught other than your slave. If all has been as carefully carried out as it has been planned, we have no time to waste. Instead we should be upon our way to the slave market. Are you ready?"

The merchant nodded, and, turning to a great chest, produced the unemblazoned trappings of a slave. These Vas Kor immediately donned. Then the two passed from the shop through a rear door, traversed a winding alley to an avenue beyond, where they entered a flier which awaited them.

Five minutes later the merchant was leading his slave to the public market, where a great concourse of people filled the great open space in the centre of which stood the slave block.

The crowds were enormous to-day, for Carthoris, Prince of Helium, was to be the principal bidder.

One by one the masters mounted the rostrum beside the slave block upon which stood their chattels. Briefly and clearly each recounted the virtues of his particular offering.

When all were done, the major-domo of the Prince of Helium recalled to the block such as had favourably impressed him. For such he had made a fair offer.

There was little haggling as to price, and none at all when Vas Kor was placed upon the block. His merchant-master accepted the first offer that was made for him, and thus a Dusarian noble entered the household of Carthoris.