Produced by Greg Weeks, Bruce Albrecht, Louise Pryor and the Online Distributed Proofreading Team at http://www.pgdp.net [Transcriber's note: This etext was produced from Astounding Science Fiction August 1959. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] THE ALIENS BY MURRAY LEINSTER Illustrated by van Dongen [Illustration] _The human race was expanding through the galaxy ... and so, they knew, were the Aliens. When two expanding empires meet ... war is inevitable. Or is it ...?_ At 04 hours 10 minutes, ship time, the _Niccola_ was well inside the Theta Gisol solar system. She had previously secured excellent evidence that this was not the home of the Plumie civilization. There was no tuned radiation. There was no evidence of interplanetary travel--rockets would be more than obvious, and a magnetronic drive had a highly characteristic radiation-pattern--so the real purpose of the _Niccola's_ voyage would not be accomplished here. She wouldn't find out where Plumies came from. There might, though, be one or more of those singular, conical, hollow-topped cairns sheltering silicon-bronze plates, which constituted the evidence that Plumies existed. The _Niccola_ went sunward toward the inner planets to see. Such cairns had been found on conspicuous landmarks on oxygen-type planets over a range of some twelve hundred light-years. By the vegetation about them, some were a century old. On the same evidence, others had been erected only months or weeks or even days before a human Space Survey ship arrived to discover them. And the situation was unpromising. It wasn't likely that the galaxy was big enough to hold two races of rational beings capable of space travel. Back on ancient Earth, a planet had been too small to hold two races with tools and fire. Historically, that problem was settled when _Homo sapiens_ exterminated _Homo neanderthalis_. It appeared that the same situation had arisen in space. There were humans, and there were Plumies. Both had interstellar ships. To humans, the fact was alarming. The need for knowledge, and the danger that Plumies might know more first, and thereby be able to exterminate humanity, was appalling. Therefore the _Niccola_. She drove on sunward. She had left one frozen outer planet far behind. She had crossed the orbits of three others. The last of these was a gas giant with innumerable moonlets revolving about it. It was now some thirty millions of miles back and twenty to one side. The sun, ahead, flared and flamed in emptiness against that expanse of tinted stars.