Somehow he began to doubt that he had killed Selba. It had been only a dream, and the monstrous thing that had sought his life had been a dream too. Hekalu was pursuing him now, trying to kill him! The idea took hold, for he could no longer distinguish fancy from reality. It brought to him a vague fear which would have been completely out of place with him had he not been so near gone from loss of blood. It was like a child's fear of the dark. He began to fly towards home in a wild zigzag course like a dazed bat, but this favored him, for it enabled him to avoid the darts from the pursuing plane. Luckily he remembered that while under fire combat fliers do not make use of their automatic pilots except as a last resort, for these devices cannot direct the complex movements necessary in dodging enemy bullets. Automatically Shelby watched the guiding instruments and followed their directions. Several times he signaled with his siren, but no one answered him. Thousands of sirens were hooting, and the Air Patrol was very busy. The darkness, the explosions and the muffled roar from the streets continued. Two ideas now possessed Shelby's mind and he clung to them with the grim persistence of a wounded tiger. One was to get home, secure his weapon and rush it to the federal authorities. The other was to hurry to Janice Darell. Presently his plane bounded down awkwardly on the landing platform of the building in which his apartment was located. He stumbled out, and down the dark stair. The elevators were not working. Somehow he found his door and unlocked it. He groped toward the wall safe. It was open, and the little black case which contained the unfinished atomic ray projector was gone. A neat round hole had been drilled in the metal door of the safe. The view-phone bell was ringing. Shelby stumbled to the instrument and moved its switches. The view-plate did not work but he heard a faint voice which he recognized as Jan's. "Is that you, Austin?" it said. "Can't you help me? Something is out there. It has me cornered in my room. It has killed old Rufus. The house police--" There the connection snapped. A wild surge of anger quickened the engineer's weakly beating heart. He tried to reach the door, and then he felt a stinging sensation in the back of his neck. A needle-dart charged with a sleep-producing drug had struck him. He slumped to the floor. A moment later a thing of metal and fabric, fitted with drills and delicate thread-like tentacles, and formed like a giant Sadu moth of Mars, darted out from behind a curtain where it had been hiding. It flew up through the air-tube which had been its means of entrance to the room. On the roof it met a black nightmare, and by means of signs traced in the air with an intelligence that was paradoxically human, it directed the monster to Shelby's apartment below. * * * * *