Suddenly it was night. The Barsoomian day had ended, and then the brief period of twilight that renders the transition from daylight to darkness almost as abrupt as the switching off of an electric light, and Tara of Helium had found no sanctuary. But perhaps there were no beasts to fear, or rather to avoid--Tara of Helium liked not the word fear. She would have been glad, however, had there been a cabin, even a very tiny cabin, upon her small flier; but there was no cabin. The interior of the hull was completely taken up by the buoyancy tanks. Ah, she had it! How stupid of her not to have thought of it before! She could moor the craft to the tree beneath which it rested and let it rise the length of the rope. Lashed to the deck rings she would then be safe from any roaming beast of prey that chanced along. In the morning she could drop to the ground again before the craft was discovered. As Tara of Helium crept over the brow of the hill down toward the valley, her presence was hidden by the darkness of the night from the sight of any chance observer who might be loitering by a window in the nearby tower. Cluros, the farther moon, was just rising above the horizon to commence his leisurely journey through the heavens. Eight zodes later he would set--a trifle over nineteen and a half Earth hours--and during that time Thuria, his vivacious mate, would have circled the planet twice and be more than half way around on her third trip. She had but just set. It would be more than three and a half hours before she shot above the opposite horizon to hurtle, swift and low, across the face of the dying planet. During this temporary absence of the mad moon Tara of Helium hoped to find both food and water, and gain again the safety of her flier's deck. She groped her way through the darkness, giving the tower and its enclosure as wide a berth as possible. Sometimes she stumbled, for in the long shadows cast by the rising Cluros objects were grotesquely distorted though the light from the moon was still not sufficient to be of much assistance to her. Nor, as a matter of fact, did she want light. She could find the stream in the dark, by the simple expedient of going down hill until she walked into it and she had seen that bearing trees and many crops grew throughout the valley, so that she would pass food in plenty ere she reached the stream. If the moon showed her the way more clearly and thus saved her from an occasional fall, he would, too, show her more clearly to the strange denizens of the towers, and that, of course, must not be. Could she have waited until the following night conditions would have been better, since Cluros would not appear in the heavens at all and so, during Thuria's absence, utter darkness would reign; but the pangs of thirst and the gnawing of hunger could be endured no longer with food and drink both in sight, and so she had decided to risk discovery rather than suffer longer.