And then the visitor realized he was holding a corpse in his arms. He laid it gently down and did as he had been directed to do. CHAPTER II _The Great Clock of Tarth_ The Plains of Ofrid on the planet Tarth stretched flat and monotonous as far as the eye could reach, a gently waving ocean of soft, knee-high grass where herds of wild stads grazed and bright-hued birds vied in brilliance with the flaming sun. From the dark Abarian Forests to the Ice Fields of Nadia, the plain stretched unbroken except for the tall, gray tower in its exact center and it was toward this tower that various groups of Tarthans were now moving. Every nation on the planet was represented in greater or lesser number. The slim, erect Nadians in their flat-bottomed air cars that could hang motionless in space or skim the surface of the planet at a thousand jeks an hour. The grim-faced Abarians, tall and finely muscled on their powerful stads, their jeweled uniforms flashing back the glory of the heavens. The Utalians, those chameleon men of Tarth, their skins now the exact color of the grasses across which they rode, thus causing their stads to appear unmounted and unguided. All the nations of Tarth were represented, drawn toward the tower by a century-old legend, a legend which Retoc the Abarian clarified as he rode at the head of his own proud group. He waved a hand, indicating the vast plain and spoke to Hultax, his second in command, saying, "Little would one think that this flat, empty land was once the site of a vast and powerful nation. One of the greatest upon all Tarth!" A smile of cruelty and satisfaction played upon his handsome features as he surveyed the plain. "Aye," Hultax replied. "The realm of the Ofridians. Truly they were a great nation." "But we Abarians were greater," Retoc snapped. "We not only defeated them but we leveled their land until not one stone stood upon another." "All save the tower," Hultax said. "No weapon known could so much as scratch its surface." * * * * * A new voice cut in. "Quite true. Portox's scientific skill was too great for you." Both Abarians turned quickly to scowl at the newcomer, Bontarc of Nadia, who had swung close in his one-man car and was hovering by their side. Retoc's hand moved toward the hilt of his long whip-like sword, driven there by the look of contempt in Bontarc's eyes. But Retoc hesitated. A formidable squadron of Bontarc's Nadian fighting men hovered nearby and the Abarian had no taste for a battle in which the odds were close to even. "We defeated the Ofridians fairly," he said. "And slaughtered them fairly? Cut down the men and women and children alike until the entire nation was obliterated?"