"Well, you needn't trouble the War Department. Here's your volunteer pilot! The plane's outside. When do we start?" "But, my dear young man!" objected the professor. "I cannot permit you to make this sacrifice. It is suicide, sheer suicide." "Is my life any more precious than yours, or that of some volunteer Army pilot?" Jim asked him. "But there is Joan. If I fail--she must depend on you." "If you fail, Professor, Joan won't need me or anyone, for long. No, I go. So let's chuck the argument and get ready." "Oh, Jimmy!" sobbed Joan. "Jimmy!" But her eyes, as they met his mistily, were lit with a proud splendor. * * * * * Two hours later, Jim Carter's little auto-plane lifted into the night, and, with that precious tube mounted above the cabin, winged swiftly westward. As on his former foray into that fiery realm, Jimmy timed his flight to arrive over the eastern edge of the Arizona desert just before dawn. Somewhere in that great sandy waste, they felt, there would be a place to set the plane down and get the ray going. Professor Wentworth had broadcast the particulars of his tube to his scientific colleagues wherever humanity still remained, and the eyes of the world were on this flight. If successful, swift planes would bear similar tubes to the centers of the devastated regions elsewhere, and sweep outward with their deadly rays. The earth would be rid of this fiery invader. If it were not successful.... Jim preferred not to think of that, as he drove on into the night. Crossing the Missouri River at dark and deserted Kansas City, they soon saw the eastern arc of that deadly orange circle loom on the horizon. To get over it safely, Jim rose to twenty thousand feet, but even there the heat, as they sped across the frontier into enemy territory, was terrific. Anxiously he watched his revs and prayed for his motor to hold up. If it stopped now, they were cooked! The sturdy engine purred on with scarcely a flutter, however, and soon they were behind the lines, in a region pitted with the smoldering fires of towns and cities. It made them shudder, it presented such an appalling panorama of ruin. But at the same time, it strengthened their hope. For very few flares of orange gleamed now among the red. The main forces of the invader were at the front. That meant there should be a safe place to land somewhere. * * * * * An hour later, some miles beyond that weird glass citadel that had been their objective, they found a wide stretch of empty desert, and there Jim brought the little plane down to a faultless landing, just as dawn was lightening the east. Stepping out, he drew a deep breath of relief. For had he crashed, or smashed that fragile tube, all would have been in vain. "Well, here we are!" he exclaimed, grimly cheerful, as Professor Wentworth stepped out after him. "Now let's--"