The ray-rods streaked their message of death into the thick of them. Yet so fierce was the rush that some parts got home. Arms, legs, and barrel chests, halves of men, covering the five with that impalpable black powder into which their bodies were dissolving. Nat remembered afterward the horror of a grinning face, apparently loose in the air, and a flailing arm that lashed his chest. For fifteen seconds, perhaps, it was like struggling with some vampire creatures in a hideous dream. And then, just when it seemed to Nat that he was going mad, he found the path free, and the huddled remnants of the Moon men piled up about him on every side. He emptied two more ray-shots into the writhing mass, and saw it cease to quiver and then dissolve into the black powder. He turned and looked at his companions. They, too, showed the horror of the strain they had undergone. "We must kill the guards now," Nat panted. "And then find Madge and save her." "We're with you," answered Brent, and together the five rushed into the sunlight and the open. * * * * * There were no guards on duty at the entrance of the house, and the door stood wide open. Nat rushed through the door at the head of his men. A single guard was in the hall, but he only looked up as they came in. And it was evident that he was in no condition to resist, for he was in the grip of some terrible disease. His features were swollen so that they were hardly recognizable, and hoarse, panting breaths came from his lungs. He was so far gone that he hardly registered surprise at the advent of the five. "Where's Axelson?" demanded Nat. The guard pointed toward the end of the corridor, then let his arm fall. Nat led his men along the half-dark passage. At the end of the corridor two more guards were on duty, but one was collapsed upon the floor, apparently unconscious, and the other, making a feeble attempt to draw his ray-rod, crumbled into ashes as Brent fired. The five burst through the door. They found themselves in the banquet-hall. The remnants of the meal were still upon the table, and three Moon men, looking as if they had been poisoned, were writhing on the floor. At the farther end of the hall was another door. This gave upon a central hall, with a door in each of its four sides, and a blaze of sunlight coming through the crystal roof. The five stopped, baffled. Then of a sudden Axelson's voice broke the silence--his voice, yet changed almost beyond recognition, hoarse, broken, and gasping: "Try the doors, Nathaniel Lee. Try each door in turn, and then go back. And know that in an instant I can blast you to nothingness where you stand!" And suddenly there came Madge's voice, "He can't! He can't, Nat. He's dying, and he knows it. I won't let him, and he hasn't got the strength to move." "Which door?" cried Nat in desperation.