From the far north another force was moving south across the barrier cliffs-the new navy of Talu, Jeddak of Okar, coming in response to the call from the warlord. Upon the decks of the sullen ships of war black-bearded yellow men looked over eagerly toward the south. Gorgeous were they in their splendid cloaks of orluk and apt. Fierce, formidable fighters from the hothouse cities of the frozen north.

And from the distant south, from the sea of Omean and the cliffs of gold, from the temples of the therns and the garden of Issus, other thousands sailed into the north at the call of the great man they all had learned to respect, and, respecting, love. Pacing the flagship of this mighty fleet, second only to the navy of Helium, was the ebon Xodar, Jeddak of the First Born, his heart beating strong in anticipation of the coming moment when he should hurl his savage crews and the weight of his mighty ships upon the enemies of the warlord.

But would these allies reach the theatre of war in time to be of avail to Helium? Or, would Helium need them?

Carthoris, with the other members of the crew of the Thuria, heard the gossip and the rumours. None knew of the two fleets, the one from the south and the other from the north, that were coming to support the ships of Helium, and all of Dusar were convinced that nothing now could save the ancient power of Helium from being wiped for ever from the upper air of Barsoom.

Carthoris, too, loyal son of Helium that he was, felt that even his beloved navy might not be able to cope successfully with the combined forces of three great powers.

Now the Thuria touched the landing-stage above the palace of Astok. Hurriedly the prince and Vas Kor disembarked and entered the drop that would carry them to the lower levels of the palace.

Close beside it was another drop that was utilized by common warriors. Carthoris touched Kar Komak upon the arm.

«Come!» he whispered. «You are my only friend among a nation of enemies. Will you stand by me?»

«To the death,» replied Kar Komak.

The two approached the drop. A slave operated it.

«Where are your passes?» he asked.

Carthoris fumbled in his pocket pouch as though in search of them, at the same time entering the cage. Kar Komak followed him, closing the door. The slave did not start the cage downward. Every second counted. They must reach the lower level as soon as possible after Astok and Vas Kor if they would know whither the two went.

Carthoris turned suddenly upon the slave, hurling him to the opposite side of the cage.

«Bind and gag him, Kar Komak!» he cried.

Then he grasped the control lever, and as the cage shot downward at sickening speed, the bowman grappled with the slave. Carthoris could not leave the control to assist his companion, for should they touch the lowest level at the speed at which they were going, all would be dashed to instant death.

Below him he could now see the top of Astok's cage in the parallel shaft, and he reduced the speed of his to that of the other. The slave commenced to scream.

«Silence him!» cried Carthoris.

A moment later a limp form crumpled to the floor of the cage.

«He is silenced,» said Kar Komak.

Carthoris brought the cage to a sudden stop at one of the higher levels of the palace. Opening the door, he grasped the still form of the slave and pushed it out upon the floor. Then he banged the gate and resumed the downward drop.

Once more he sighted the top of the cage that held Astok and Vas Kor. An instant later it had stopped, and as he brought his car to a halt, he saw the two men disappear through one of the exits of the corridor beyond.

The morning of the second day of her incarceration in the east tower of the palace of Astok, Prince of Dusar, found Thuvia of Ptarth waiting in dull apathy the coming of the assassin.

She had exhausted every possibility of escape, going over and over again the door and the windows, the floor and the walls.

The solid ersite slabs she could not even scratch; the tough Barsoomian glass of the windows would have shattered to nothing less than a heavy sledge in the hands of a strong man. The door and the lock were impregnable. There was no escape. And they had stripped her of her weapons so that she could not even anticipate the hour of her doom, thus robbing them of the satisfaction of witnessing her last moments.

When would they come? Would Astok do the deed with his own hands? She doubted that he had the courage for it. At heart he was a coward-she had known it since first she had heard him brag as, a visitor at the court of her father, he had sought to impress her with his valour.

She could not help but compare him with another. And with whom would an affianced bride compare an unsuccessful suitor? With her betrothed? And did Thuvia of Ptarth now measure Astok of Dusar by the standards of Kulan Tith, Jeddak of Kaol?

She was about to die; her thoughts were her own to do with as she pleased; yet furthest from them was Kulan Tith. Instead the figure of the tall and comely Heliumite filled her mind, crowding therefrom all other images.

She dreamed of his noble face, the quiet dignity of his bearing, the smile that lit his eyes as he conversed with his friends, and the smile that touched his lips as he fought with his enemies-the fighting smile of his Virginian sire.

And Thuvia of Ptarth, true daughter of Barsoom, found her breath quickening and heart leaping to the memory of this other smile-the smile that she would never see again. With a little half-sob the girl sank to the pile of silks and furs that were tumbled in confusion beneath the east windows, burying her face in her arms.

In the corridor outside her prison-room two men had paused in heated argument.

«I tell you again, Astok,» one was saying, «that I shall not do this thing unless you be present in the room.»

There was little of the respect due royalty in the tone of the speaker's voice. The other, noting it, flushed.

«Do not impose too far upon my friendship for you, Vas Kor,» he snapped. «There is a limit to my patience.»

«There is no question of royal prerogative here,» returned Vas Kor. «You ask me to become an assassin in your stead, and against your jeddak's strict injunctions. You are in no position, Astok, to dictate to me; but rather should you be glad to accede to my reasonable request that you be present, thus sharing the guilt with me. Why should I bear it all?»

The younger man scowled, but he advanced toward the locked door, and as it swung in upon its hinges, he entered the room beyond at the side of Vas Kor.

Across the chamber the girl, hearing them enter, rose to her feet and faced them. Under the soft copper of her skin she blanched just a trifle; but her eyes were brave and level, and the haughty tilt of her firm little chin was eloquent of loathing and contempt.

«You still prefer death?» asked Astok.

«To YOU, yes,» replied the girl coldly.

The Prince of Dusar turned to Vas Kor and nodded. The noble drew his short-sword and crossed the room toward Thuvia.

«Kneel!» he commanded.

«I prefer to die standing,» she replied.

«As you will,» said Vas Kor, feeling the point of his blade with his left thumb. «In the name of Nutus, Jeddak of Dusar!» he cried, and ran quickly toward her.

«In the name of Carthoris, Prince of Helium!» came in low tones from the doorway.

Vas Kor turned to see the panthan he had recruited at his son's house leaping across the floor toward him. The fellow brushed past Astok with an: «After him, you-calot!»

Vas Kor wheeled to meet the charging man.

«What means this treason?» he cried.

Astok, with bared sword, leaped to Vas Kor's assistance. The panthan's sword clashed against that of the noble, and in the first encounter Vas Kor knew that he faced a master swordsman.