The arm began contracting. Powell was helpless against the terrific power of the slender, diamond-hard lance of crystal. He felt himself irresistibly drawn toward the silver-faceted wall of the Devil Crystal. His senses reeled in the babel of alien sounds--the crashing, glass-like music of the crystalline monsters and the snarling, squealing, paean of jubilant triumph from the thousands of rat-men now lining the rim of the pit above. * * * * * Then suddenly the pit, the Devil Crystals, and everything else in the nightmare world of Arret was blotted out in a vast swirling cloud of pulsing roseate flame that seemed to sweep him bodily up into the air and whirl him dizzily around. His dazed brain staggered from the shock of the cataclysmic force that was disintegrating an entire world around him, but through the utter chaos one thought rang clear and exultant in his consciousness. Benjamin Marlowe had finally broadcast the recall wave! For what seemed endless eons of time Powell hurried through a limitless universe of swirling, tinted fires, while vibrations of a mighty force tingled with poignant ecstasy in every atom of his body. Then the eddying clouds of flame began to coalesce and solidify with startling suddenness. A moment later, like the abrupt lighting of a room when an electric switch is snapped, the mists vanished and Powell felt firm footing again under his feet. Around him were the familiar objects of Benjamin Marlowe's laboratory. He was standing upon the floor-plate in the center of the area bounded by the banked green tubes, and beside him stood Joan, sobbing with relief at their last-minute rescue from the Devil Crystals of Arret. And over by the control panel of the recall mechanism was the slight figure of old Benjamin Marlowe, with a great joy now shining in his faded eyes.