The beast took a sudden step forward, and Gates found himself almost projected off the platform as the monster shot out at him, "Do you not think we brought you to the Planetoid for a purpose? For a long while, have we not been looking for suitable earth-captives? No, not at first members of the common pack! We wanted prisoners who knew something of your science, rudimentary as that is. When you went to the roof down there to use your ray machine--the Infra-Red Eye, as you call it--you set up etheric vibrations that instantly attracted our attention. Your ability to produce such vibrations told us that you were the folk we were seeking. So we lost no time about capturing you." During the moment of silence that followed, Dunbar turned toward Gates with unveiled enmity in his snapping black eyes. "So!" he snarled. "It was your damned invention that got us into this mess!" Gates made no reply; but an answer came from an unexpected direction. "You should thank him, earth-man, for getting you into this mess. Because of his invention, you three may live while all other earth-creatures perish!" "What in God's name would life on such terms be worth?" Gates demanded. But a sob to his left caught his attention; and, wheeling about, he joined Dunbar in trying to console the weeping girl. With a contemptuous glint in his triangular eyes, Red-Hood stood looking on; but it was several minutes before he resumed, "Life is dear to all creatures--and you will find it not worthless on our terms!" "What are your terms?" It was Dunbar who asked this question, while Gates felt a silent resentment against the other man leap up within him. "They are really most reasonable," the monster announced, sliding back and forth on the web, while his scales clanked ominously. "You see, even after all we have done, we find it hard to work on earth. The air is much too thin. After we have thickened the atmosphere with a complete network, things will be different; but as yet we labor under great disadvantages. What we need are tanks of compressed air to help our breathing. Such compressed air can be supplied only by you earth-creatures, since in our haste, unfortunately, we neglected to bring our automatic condensers from Saturn. That is why we have captured you. And that is why we promise you your lives--if you will do us a little service." Gates glared back at Red-Hood in unconcealed fury. That this creature, who was threatening to wipe out the human race, should ask for his assistance--the idea was too preposterous, too heinous for consideration! And he was glad to note, from the revulsion in Eleanor's face, that she felt no less shocked than he. But it was in unbelief, swiftly turning to anger, that he heard Dunbar's low, even voice, inquire, "And what little service do you want of us?" The gray-green lips of the Saturnian opened in a hideous grin.