Doomsday 257 A.G.!

Prince Cadmus slew the Dragon and sowed its teeth. Could this latter-day Cadmus smash Akal-jor's atomic monster? Could he halt the devouring Gray God before—
Cadmus trembled now as he waited. He had been waiting too long. Sweat was heavy on his clean-muscled body. A bright eagerness blazed from his gray eyes. And beyond the small pressure dome of the combination lab and living quarters, the frigid night pounded at the translucent teflonite—gnawed hungrily at that small dot of life and warmth on the barren asteroid.
Now that he was almost ready to step into the matter transmitter, each moment had become an eternity as he waited to be transported almost instantly to Mars. To the city of Akal-jor. To his final destiny.
He cursed softly at the cloud of amnesia aching in his skull. Johlan the Venusian scientist had had him in various states of hypnosis for some time, educating him for this task, and had placed a protective veneering of amnesia across his mind to protect his purpose from the Silver Guard's mental probers in case he were captured.
Since birth, Johlan had raised Zaleel and Cadmus on the asteroid. The three of them were unconditionally dedicated to the great plan. Because of his fogged memory, Cadmus now knew but little concerning the details of the plan. He only knew that he would die to carry it through. That if he failed, Tri-Planet civilization would go on down to final decay and ruin.
The three of them, three frail motes of intelligent life, must save the vast System. Old Johlan the Venusian. Zaleel of the golden hair and generous red lips. And Cadmus the fighter. To fight the Silver Guards, and the gigantic mechanical intelligence of the Great Gray God, Cadmus had only the sword at his side and the crude energy gun Johlan had made. The energy gun was too small for efficiency but it had to be small in order to be carried unnoticed beneath his tunic.
Zaleel was gone. She had stepped into the transmat months before to carry out her part of the plan. Cadmus remembered only the shiny richness of her hair, the warm promise of her lips.