"It's impossible!" Ketrik said. "Those Outlanders hate the Upper Martians with a hatred beyond our understanding. Nothing would impel them to make truce, absolutely _nothing_! I know, for I once lived among them for six months." Ketrik was as near to being excited as was possible for him. "Yes, Mark, I'll go to Mars. This really begins to interest me!" II They spent much of that night in going over their plans. Ketrik had no misapprehensions about landing on Mars; he could do that despite Vaajo's patrols. Turibek presented the real problem. Carefully he perused the tele-strip recordings from Mark's operatives, E-39 and EV-5. There had only been two reports, and they were brief. "This last one was sent two weeks ago," Mark said, "and I haven't been able to contact them since. The channel's dead. I'm afraid it means their hide-out was discovered!" Ketrik studied the rough map Mark had made, showing the location of the hide-out in the K'Mari Range, and its position from Turibek. "This will help. I'll try to get over there, see if anything's left of their sending equipment. Then I want to make a try for the city. If I can get inside of Turibek, and maybe get a line on this scientific thing they're working up ... I was at Turibek eight years ago, and know it fairly well." "Here's a photo-static air view," Mark said. "Afraid it doesn't show much." "It shows one thing," Ketrik said, studying the film. "Dar Vaajo's had a wall built completely around the city. That wasn't there eight years ago! And those towers stationed around the wall--what do you suppose they are?" "Control towers. That's an electronic wall! And you'll observe there's another within the city itself, surrounding that group of buildings which must be the laboratories. Ketrik--if you ever get in there...." His voice dwindled away in doubt. "You don't think I can do it? I don't either, Mark--not as an Earthman!" "Come. We'll fix that." They passed through endless corridors, arrived finally at a large white-enameled room. It was complete with operating tables, instruments, plastics, ray-lamps--everything necessary to Earth's espionage system. Ketrik stripped piecemeal, allowed every inch of his superbly muscled body to be subjected to the stinging Ulmo lamps. Gradually under the hot rays, the very pigmentation of his skin changed to the deep reddish-copper of a Martian. Mark proved himself an expert at this. Even the insides of Ketrik's ears did not escape the ray. "Don't worry," Mark told him. "This will all wear off eventually." "Yes? How long?" "In about two years! Now, your eyes. You never saw a Martian with gray eyes. Look up just a moment." A few drops of liquid, a harmless vegetable composition, changed Ketrik's eyes to a muddy golden color.