Syme murmured something and turned away, feeling the spaceman's eyes on the small of his back until he turned the corner. At the next street he took a ramp up, crossed over and came down on the other side a block away. He waited until he saw the boy's broad figure pass the intersection, and then followed again more cautiously. It was risky, but there was no other way. The signatures, the data, even the photograph on the card could be forged once Syme got his hands on it, but the identity card itself--that oblong of dark diamondite, glowing with the tiny fires of radioactivity--that could not be imitated, and the only way to get it was to kill. Up ahead was the Founders' Tower, the tallest building in Lillis. The boy strode into the entrance lobby, bought a ticket for the observation platform, and took the elevator. As soon as his car was out of sight in the transparent tube, Syme followed. He put a half-credit slug into the machine, took the punctured slip of plastic that came out. The ticket went into a scanning slot in the wall of the car, and the elevator whisked him up. * * * * * The tower was high, more than a hundred meters above the highest level of the city, and the curved dome that kept air in Lillis was close overhead. Syme looked up, after his first appraising glance about the platform, and saw the bright-blue pinpoint of Earth. The sight stirred a touch of nostalgia in him, as it always did, but he put it aside. The boy was hunched over the circular balustrade a little distance away. Except for him, the platform was empty. Syme loosened his slim, deadly energy pistol in its holster and padded catlike toward the silent figure. It was over in a minute. The boy whirled as he came up, warned by some slight sound, or by the breath of Syme's passage in the still air. He opened his mouth to shout, and brought up his arm in a swift, instinctive gesture. But the blow never landed. Syme's pistol spat its silent white pencil of flame, and the boy crumpled to the floor with a minute, charred hole in the white leather over his chest. Syme stooped over him swiftly, found a thick wallet and thrust it into his pocket without a second glance. Then he raised the body in his arms and thrust it over the parapet. It fell, and in the same instant Syme felt a violent tug at his wrist. Before he could move to stop himself, he was over the edge. Too late, he realized what had happened--one of the hooks on the dead spaceman's harness had caught the heavy wristband of his chronometer. He was falling, linked to the body of his victim! Hardly knowing what he did, he lashed out wildly with his other arm, felt his fingertips catch and bite into the edge of the balustrade. His body hit the wall of the tower with a thump, and, a second later, the corpse below him hit the wall. Then they both hung there, swaying a little and Syme's fingers slipped a little with each motion.