"I'm hiding," snapped Bartol. _He knows where I am now. I'll have to work fast._ He pressed his thumb against a hidden niche in the wall. A tiny device recorded his thumbprint, checked it against previous patterns, and then clicked. A panel slid aside. Within it was a curiously shaped helmet. Bartol could hear the pounding of android feet all around him. Nearby, a wall started to smoke. He slammed the helmet on his head, locked the chinpiece into place, and activated the mechanism within the dome. "Where are you? What was that helmet? The assassin is coming down!" Evidently, the now-panicky Commander was watching him in the vision screens. He wouldn't see anything now; Bartol was invisible to infrabeams. Unfortunately, he was still visible to normal vision. The nearby wall cascaded outward with a splash of molten metal, and an android stepped through, firing a heavy beam-rifle. The beam struck Bartol with a glare of blue-white light--and splashed. With the helmet on, Bartol was just as impervious to ordinary beams as the assassin who was even now burning his way down through the Palace. Like the assassin, all he had to do was avoid anything as heavy as a semiportable. Bartol stepped directly into the blazing muzzle of the rifle. The tremendous energy being reflected from his body shield dazed the android. Bartol jerked the rifle from its hands and burned it down. He swung around just as two more of the things rounded a nearby corner. They, too, went down before the white-hot beam of the rifle. Then he stepped toward the wall. Under the tremendous power of the special body shield, the wall flowed like wax in a candle flame. It hardly slowed him at all. He stopped for a moment, concentrating. Where was his enemy? Dimly at first, then with greater power, the intricate amplifier of the helmet picked up the brain radiations of the man he was looking for. In his ear, the speaker was still gibbering. Bartol stood a moment longer, synchronizing the helmet with the signals. Then, having located his enemy, he began to move again. He headed for the elevators. There was only one. The other ended two levels above. It must be the one. He pushed his way through the door and dropped down the open shaft. The antigravity field allowed him to drop rapidly, but not too rapidly; even that marvelously designed helmet couldn't do everything. It would slow his fall somewhat, but it couldn't lift him. His feet struck the top of the elevator car whose cables he had cut. He changed the polarity of his field and the force was applied vertically instead of radially. His feet melted their way through the top of the car. He reversed the polarity again before he touched the floor of the car. The assassin upstairs was running amok, burning down everything in his path and working his way downwards. * * * * *