The impact carried the Guard backward. Their combined weight crashed into a door, nearly taking it from the hinges. Ketrik rose quickly but the Guard didn't rise at all, and Ketrik knew his luck was still with him. He changed his mind a second later. He heard shouts and pounding feet. Guards were all about the place, probably stationed at each of the doors! For a split second Ketrik hesitated. The only way now, was _in_. He hurled his weight forward and the already weakened door crashed open. * * * * * He hurried recklessly forward through darkness. He touched a smooth marble wall, allowed his fingertips to brush lightly along it as he ran. His racing feet sent up echoes in the hollow place. The Guards were crowding through the doorway behind him now. Suddenly lights leaped up! Just as suddenly, Ketrik swerved aside. An electro-beam hummed, came so close to him he could feel the swirling heat. He hurled himself into a dim cross-corridor, as more electros lanced out. But Ketrik was expert at this game. He raced for a stairway he could see just ahead. He was halfway up when the others came into view below him. He whirled, gave a sweeping burst with his own gun that sent them tumbling back out of range. He gained the second floor corridor. Suddenly the lights came on there too! Someone at the master-switch was throwing on light all over the place! Ketrik preferred darkness. He couldn't keep this up interminably. Feet pounded on the stairs now. He opened the nearest door, slipped into a dark room. There he stood breathing heavily as the pursuers pounded by. He waited until their footsteps died away, then opened the door a crack. It was almost his undoing. A beam creased his hair. He drew back, then suddenly flung the door wide and fired at the man they had left to guard the stairs. His beam sliced across the Guard's wrist, sent his gun spinning. But the man's scream of pain sent up shrill echoes that would bring the others back. Ketrik bowled the man aside as he leaped for the stairs leading up. At least he'd gained a few minutes! He wasn't fleeing blindly now. He had an objective. He was sure the place he sought lay _above_--somewhere near that great, curved glass roof. He reached the third floor and continued upward. Then he groaned. The stairs ended at the next floor. A heavy metal door barred his way. He wasted precious seconds fumbling at the complicated mechanism--was about to use his electro to burn it away, when the great handle slid down under his pressure and the ponderous door swung aside. He leaped forward into more darkness. There he paused, electro raised. This would be cutting off his own retreat, but he had to do it now! The beam lashed out, played across the door's inner mechanism. Gradually the tough metal fused under the heat. Ketrik made a thorough job of it, was satisfied at last that it would take them some time to blast through!