That last thought gave Ketrik his answer, a temporary one at least. At dawn the caravan moved. The six Martians were surprised at this newcomer, but not yet suspicious. Ketrik didn't give them time to be. From beneath his arm-pit he produced the thin disk which he'd taken from the slain Martian operative. He flashed it briefly, asked a few curt questions, and the men were properly cowed. Apparently they knew the power of Vaajo's Specials. "Just routine," Ketrik told them. "I'll travel along with you for a while." Determined to play his role to the hilt, he added, "We can't be too careful in these times. There may be _S'Relah_ among these damned Rajecs, but we'll find them out before we get to Turibek. Dar Vaajo has gone too far in his plans to have them thwarted now." By tactful conversation he sought to learn something of what was going on at Turibek. It soon became apparent that these bedraggled men didn't know, and cared less. One of them had heard of Dar Vaajo coming to Turibek with a complete staff of scientists, but that's as far as his knowledge went. Another of the men had heard of the treaty, and wasn't surprised. "I've seen it coming," he said gruffly. "Many years I've lived in these deserts, and I tell you the Rajecs aren't the same. Especially the last few years. Something just seems to have gone out of them." Something indeed had gone out of the Rajecs, if they made treaty! Ketrik wondered what kind of magic Dar Vaajo had used to bring that about. More particularly, _why_! There was some sort of link here, between the Rajecs and whatever was going on at Turibek. And that, in turn, was a pivot in Vaajo's larger plan, the plan that would deal with Earth. Ketrik just couldn't piece it together as yet; he'd have to get to Turibek. He thought fleetingly of those electronic walls.... The sun climbed higher, hot and dry, sapping the strength. Ketrik marvelled at the long line of marching Rajecs--there were perhaps two hundred. Long years in these deserts had inured them to discomfort. Again he wondered why they were going to Turibek. Almost he was tempted to go up and speak again with the Rajec leader--the man's name was Aarnto, he learned--but he thought better of it. At high noon they stopped for rations, and a few hours later the Martian 'copters came over. They came from the direction of the city, circled once, and flew leisurely back. Ketrik wondered what that meant. He was soon to know. * * * * * Presently Aarnto dropped back, fell into step beside him and drew him away from the others. "You saw the 'copters?" "Yes," Ketrik replied. "Trouble ahead?" "For you, perhaps, O mysterious one from out of the desert! Those 'copters mean there is a surveying station ahead, and the Specials will be there. Apparently they are still searching for the spy." "These surveying stations--what do they do there?"