Half a dozen flying cars rested on a broad platform on top of one of the walls of the city of Moorn. Many bells were tolling the noonday chimes as Gerry Norton led his armored men from the _Viking_ aboard the compact little flying machines. There was room for six men in each car, the pilot and five passengers. Only Angus and the necessary assistants had remained behind to repair the space-ship with the materials supplied by the men of Moorn. Gerry leaned from his car to shake hands with Gool, who was leaning on his gold-tipped staff. "Thanks for this much help," Gerry said. "Next time we meet I'll tell you...." "We shall not meet again, my friend," Gool said with a half smile. The words seemed definitely ominous to Gerry, but before he could say anything more the old man had bowed ceremonially and then stepped back off the landing platform. The flying cars of Moorn were shallow bowls of some gleaming blue metal, oval in shape and with three comfortably upholstered seats. They had no visible means of propulsion. Curved windshields of heavy glass protected the passengers from the air-blast of swift motion. Gerry got in beside the pilot of the leading car, who was a slight and taciturn Moornian with the big head and high forehead of his race. A complicated control board was fixed in place before him. Closana and Portok were in the seat next behind, while two more members of the _Viking's_ crew occupied the rear seat. "Ready?" the pilot asked. Gerry nodded. The pilot touched a switch on the control board before him, and three globular dials glowed with an iridescent light. The space-car rose easily from the landing platform, moving upward and outward at a steep angle. There was neither noise nor vibration. The city vanished as soon as they passed outside the zone of dimensional-control on its outer walls. Looking back and down, Gerry saw only the pitted rock of the foundations far below. A cart was moving toward the beach with some bars of metal for the _Viking_. Then the next flying car came into sight as it sped out beyond the walls. Its nose came into sight first, then the middle section, finally the whole car. One after another, the rest of the flotilla took off till they were flying in a V-shaped formation like a flock of wild geese. "What kind of power makes these cars go?" Gerry asked. "Iso-electronic rays," the pilot replied shortly, not taking his eyes from the indicator board. "And can they be made invisible like the city?" "Yes. The dimensional-control lever is here." The pilot pointed at many of the controls, then again lapsed into silence.