Then they were dropping; falling clear of the mother ship. The pilot pressed a button and the electronic motors started. A burst of roaring energy streamed from the tapered stern of their vessel and the earth lurched violently to meet them. Down, down they dived until the rocking surface of Dorn was just beneath them. Then they flattened out and circled the vast upper surface. From the corner of his eye Karl saw that the other four vessels of his fleet were just behind. There was a flurry among the wasplike clouds of pleasure craft over the city. They scurried for cover. Something was amiss! "Hurry!" shouted Karl. "The warning is out! There is no time to lose!" He pressed his face to the eye-piece of his sight, his finger on the release lever of the ray. The crystal pyramid crossed his view and was gone. Again it crossed, more slowly this time. And now his sight was dead on it, the gleaming wall rushing toward him. Pressure on the tiny button. They'd crash into the palace in another second! But no, a brilliant flash obscured his vision, a blinding light that made the sun seem dark by comparison. They roared on and upward. He took his eye from the telescope and stared ahead, down. The city was dropping away, and, where the crystal palace had stood, there was a spreading blob of molten material from which searing vapors were drifting. The roofs of the city were sagging all around and great streams of the sparkling, sputtering liquid dripped into the openings that suddenly appeared. Derek Van Dorn was avenged. "Destroy! Destroy!" yelled Karl madly. A microphone hung before him and his words rang through every vessel of his convoy. * * * * * The lust of battle was upon him. A fleet of the Zar's aeros had risen from below; twenty of them at least. These would be manned by Moon creatures, he knew, and would carry all of the dreadful weapons which had originated on that strange body. But he did not know that his own ships were insulated against most of the rays used by the Zar's forces. He knew only that he must fight; fight and kill; exterminate every last one of the Zar's adherents or be exterminated in the attempt. Kill! Kill! The madness was contagious. His pilot was a marvel and drove his ship straight for the massed ships of the foe. The air was vivid with light-streamers. A ray from an enemy vessel struck the thick glass of the port through which he looked and the outer surface was shattered and pock-marked. But a cloud of vapor and a dripping stream of fiery liquid told him his own ray had taken effect on a vessel of the enemy. One! They wheeled about and spiraled, coming up under another of the Zar's aeros. It vanished in a puff of steam and they narrowly missed being covered by the falling remnants of incandescent liquid. Two! Karl's aim was good and he gloated in the fact. Three! They climbed and turned over, dropping again into the fray. Four!