He went through the man's clothes, found nothing of interest until he came under the left arm-pit. There, next to the skin, he found a tiny metal disk. He rose, went over to the wall-light to examine his find. The disk was perforated with queer Martian characters. Ketrik knew Martian, but he couldn't quite make these out. He bent closer. A sixth sense warned him, or perhaps it was some slight sound. He whirled. The Martian's hand had moved, was now grasping the electro which he swung up into line. Ketrik's hand dropped and he fired his own heat-beam from the hip. The beam cut a clean swath across the other's chest, and he died without so much as a sigh. "Sorry, buddy, whoever you are," Ketrik whispered. "Guess I'd have had to do that anyway, though. When Dar Vaajo plants Specials like you on Earth, we don't play for fun!" He fastened the identification disk under his own arm-pit. Five minutes later, from the starboard lock, he dumped the body into space and without a qualm, rayed it to dust. Then, champing with impatience, Ketrik allowed his "freighter" to plod Moonward. He skirted within five thousand miles of it, then with the satellite as a shield between him and Earth, he charted for Mars. His brush with the Martian operative had sobered him. He began to realize that Mark had every reason for alarm! The subtle tampering with the Council's mental patterns, the placing of operatives in high Earth positions, the secret scientific experiments on Mars--they all had to tie in. He was sure of one thing now. Dar Vaajo, an embittered old man, was making one last bid which would bring his race to its former glory or else carry it forever to extinction with him. There were surely other Martian operatives on Earth, and they would have established a communications base. By this time they had undoubtedly flashed the news of his coming. Ketrik smiled inwardly. Very well--they'd be expecting him at Turibek, but he'd take the indirect approach. All the way to Mars his mind was at work. He was remembering days he'd spent in that wild desert country of South Mars. From the tide of his thoughts he segregated events ... places and people ... the canals and cruel deserts, the customs of the Rajecs, those fierce black outcasts from the cities of Mars. He knew that before he got through to Turibek, he'd need all this. Already a plan was forming.... Twenty hours later he sighted a Mars patrol, six formidable spacers athwart the Earth-route. They moved leisurely, in perfect formation, and Ketrik knew their network of "finder beams" covered a large area. However, the power-principle of the Frequency Tuner defied those "finders." No challenge came through his open radio, which meant they hadn't sighted him yet.