That there was an alliance between Mars and the Moon seemed almost unbelievable. How had they managed the first contact, the first negotiations leading to the compact between two such alien peoples? Had there been any flights exchanged by the two worlds, surely the scientists of Earth would have known about it. But there had not, though there had been times and times when Sarka had peered closely enough at the surface of both the Moon and of Mars to see the activities, or the results of the activities, of the peoples of the two worlds. Somehow, however, communication, if Sarka the Second had guessed correctly, had been managed between Mars and the Moon; and now that the Earth was a free flying orb the two were in alliance against it, perhaps for the same reason that the Earth had gone a-voyaging. * * * * * Side by side sat Sarka and Jaska, their eager eyes peering through the forward end of the flashing aircar toward the Earth, growing minute by minute larger. They were able, after some hours, to make out the outlines of what had once been continents, to see the shadows in valleys which had once held the oceans of Earth.... And always, as they stared and literally willed the cubes which piloted and were the motive power of the aircars to speed and more speed, that marvelous display of interplanetary fireworks which had aroused the concern of Sarka the Second. What were those lights? Whence did they emanate? Sarka the Second had said that they came from Mars, yet Mars was invisible to those in the speeding aircars, which argued that it was hidden behind the Earth. There was no way of knowing how close it was to the home of these rebels of Dalis' Gens. And ever, as they flashed forward, Sarka was recalling that vague hint on the lips of Jaska, to the effect that Luar, for all her sovereignty of the Moon, might be, nonetheless, a native of the Earth. But.... How? Why? When? There were no answers to any of the questions yet. If she were a native of Earth, how had she reached the Moon? When had she been sent there? Who was she? Her name, Luar, was a strange one, and Sarka studied it for many minutes, rolling the odd syllables of it over his tongue, wondering where, on the Earth, he had heard names, or words, similar to it. This produced no result, until he tried substituting various letters; then, again, adding various letters. When he achieved a certain result at last, he gasped, and his brain was a-whirl. * * * * * Luar, by the addition of the letter _n_, between the _u_ and the _a_, became Lunar, meaning "of the Moon!" Yet Lunar was unmistakably a word derived from the language of the Earth! It was possible, of course, that this was mere coincidence; but, taken in connection with the suspicions of Jaska, and the incontrovertible fact that Luar resembled people of the Earth, Sarka did not believe in this particular whim of coincidence. Who was Luar?