* * * * * For long tense minutes Blake forced himself to remain rigidly motionless while Zehru labored over Mapes. Then finally the Xollarian turned his attention briefly back to Blake, and thrust two tentacles in to grip his body. No sooner had the tentacles crossed above the border of the cloth than Zehru realized that something was wrong. He tried to whip his arms back again but too late. Blake made a lightning snatch at a tentacle with both hands, and in the same lithe movement turned from the barrier wall and flung himself headlong toward the center of the enclosure. Zehru had no time to brace himself. He was jerked bodily through the shimmering wall and on after Blake's lunging body. One of the Xollarian's waving tentacles grasped wildly at the overhead disk in an effort to stay his flight. The only result was to bring the entire disk and its supports crashing in ruins to the ground upon the struggling figures of Blake and himself. Blake was upon his feet again instantly. Snatching up a yard-long scrap of metal from the wreckage of the disk, he flung himself upon Zehru. The Xollarian seemed for the moment too dazed by his fall to fight back. With tentacles raised to guard his head, he staggered backward in retreat, every step taking him farther away from the wall and the purple mists. Blake was vaguely aware that Helen and Mapes, freed by the wrecking of the disk, were scrambling to their feet. Mapes was already running toward the combatants. Blake was glad at the prospect of an ally. Zehru's dazed condition was swiftly passing. He had now stopped his retreat and was already fumbling a tentacle toward the tube-weapon in his belt. Blake flung himself upon Zehru in another effort to beat him down before he could draw that weapon, but his metal club glanced harmlessly off the tentacles Zehru raised to shield his head. Then beyond Zehru Blake saw something that made him stop his assault. * * * * * It was Mapes, sprinting toward the silver arch-gate at the other end of the enclosure. Blake's heart sank as he realized the gangster's treachery. If he once reached that arch he could send himself safely hurtling back to Earth, while Blake and Helen would be left to perish with Zehru in the explosion that would immediately follow. It was too late for Blake to head the gangster off. He had already covered half the distance to the arch. Zehru noted Mapes' fleeing figure almost as quickly as did Blake. Swiftly the Xollarian swung his tube-weapon into line with the fleeing gangster. A thin pencil of dull yellow light of a peculiar density spurted from the tube toward Mapes. There was a flash of blinding flame as the light beam met the gangster's body; then Mapes' figure seemed to literally explode, as though blasted by dynamite from within. So devastating was the force of that explosion that nothing remained of Mapes' body beyond a few scattered fragments of shoes and clothing.