The Friendly Killers By S. M. Tenneshaw How do you fight an alien race invisible to Terran eyes? Particularly when you suspect your enemy is really masquerading as an ally! [Transcriber's Note: This etext was produced from Imagination Stories of Science and Fantasy June 1958 Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] "Mankind never learned where the Kel came from. They were, apparently, a remnant of some uncontacted island culture. "The first hint the FedGov had of their existence was the sudden appearance of their strange silver globeships off Cadar. Sweeping down with not even an effort to communicate with the helpless inhabitants, the Kel desolated the entire planet. Other outlying worlds met the same fate. "Then the FedGov rallied. A rigid defense net was set up, and the controversial compulsory conditioning laws enacted. "But since the Kel maintained no fixed base of operations, it seemed impossible to strike any really damaging blow against them. "The result was a stalemate, in which neither side appeared able to gain any real advantage. "This situation continued for well-nigh two hundred years, until a disastrous break through in which the Kel wiped out the entire population of Bejak II. "The next four years saw a whole series of renewed assaults on the human race. Interplanetary shipping was disrupted so badly that in many areas worlds were virtually without mutual contact save through the limited and highly restricted facilities of FedGov space-warp. "The final climax developed on the bastion world of Rizal, when it became apparent that in this struggle man was faced with enemies within...." —Hedikawa, GALACTIC HISTORY CHAPTER I THE LUCKY ONES Outside the space-warp chamber, Rizal's great green sun had already set. Thick olive dusk eddied through the interplanetary transit center.