CHAPTER 1

 Jonner's hand dropped to his pistol and he edged cautiously behind a big rock as another groundcar appeared among the dunes to the south and approached the little group of men. He was sure Sir Stanrich had told him there were to be four others in his little task force: and there were four with him now. But the new groundcar did not approach like a hostile patrol car. There was an air of confidence about the way its driver swung it up to the others. Jonner held his hand, thinking furiously, as the airtight door swung open and the newcomer leaped lightly to the ground. The sun was settling over the iron-red wastes of the Isidis Desert. The groundcars clustered like giant beetles at the top of the cliff that dropped straight down to the shadowed lowland of Syrtis Major. The six men in marsuits, huddled at rendezvous, kept their helmet radios low, for Mars City was less than fifty miles east of them. With the twilight, the blue mist of Mars was beginning to settle toward the ground. Jonner debated with himself. Could he have misunderstood Sir Stanrich? Or could the plans have been changed after he left the Isidis spaceport? No. Then who was the sixth man? And which man was he? "Regina fell right after I left," said the burly, gray-haired man. That would be Tyruss, the former space captain, who had come here from Regina. "Our troops were falling back along the Hadriacum Lowland. I suppose they plan to make a stand before Charax." "No, Charax is to be evacuated tonight," said Jonner, and savored the shock of that announcement on his hearers. He studied the credentials each man had handed him on arrival. There was Tyruss, from Regina. There was Farlan, an astrogator from the Rebel defenses in the Strymon Canals, and there was Aron, who had just arrived, a space engineer from the Hadriacum front. There were Stein, an astrogator, and Wessfeld, an engineer, who had come together in one groundcar from Charax. The credentials were all alike, except the names. But one of them was—must be—a Marscorp spy.