The door yawned open. Twenty feet beyond, drawn up at the near wall of the great ditch, was a tracto-car. And before that car there were three men preparing to board. Jimmy stared as he recognized the foremost of the three. Hamilton Garth! The Trust Company official stood there calmly in the glare of the torch, waiting for him to approach. "What the devil are you doing here?" Garth demanded. It was a tight question, but fortunately Garth was so absorbed in his own plans and movements that he did not wait for an answer. "Sloan and Barker," he said shortly, waving his hand toward his two companions. "I.P. men. We're trailing the Nebula." "But I thought nothing was stolen from your office," Jimmy said slowly. "You said...." Garth scowled. "Money, tangibles, no. But prestige, tremendously. Do you realize, sir, what it will mean when the public learns that a cheap cracksman can walk into my vault as if it had a revolving door? I've offered fifty thousand _plantoles_ for the arrest of the Nebula, and I'm going to set an example by being the first to start on his trail." "I see." Jimmy studied him in thoughtful silence. "And his trail starts here?" "In the canal, yes. We received an unsigned tip half an hour ago that the Nebula was heading south down Canal Grand. You're coming with us, of course." As the tracto-car rocketed dizzily down the huge ditch, Jimmy hunkered down in the tonneau seat and let his thoughts run wild. This tip Garth had spoken of.... Could it be that she...? He forced his eyes toward the way ahead, deliberately guiding his mind into other channels. It wasn't the first time he had been in the canals, but it was the first time he had penetrated this far. The powerful triple-beam atolight cut a swath of radiance ahead like a chalkmark on a blackboard. Revealed in its glare were the mountainous-high walls of red stone on either side, the red floor between, hard packed, smooth as a pavement. Dimly in the reflected glow he could see the serrated lines high up near the top of the near wall, the marks of the ancient water levels, and at intervals he could see the crumbling ruins of a counting depot. What glory, what pomp and circumstance this mighty ditch had seen. Gilded canopied barges of the first and second dynasty kings, military floats, ore and shipping rafts, all drifting in an endless procession across the arid wastes of the Red Desert. Army transports loaded with armored troops advancing and retreating, converging through the labyrinthian network of subsidiary canals to battle the capital itself. And today the wonders of the past were on the verge of being repeated. Engineers were struggling frantically to overcome the one problem that so far had baffled them--the finding of a supply of _pxar_ sufficient to rebuild the locks. Ahead a lone Kiloto swooped out of the darkness into the span of light, whirled frantically and missed the onrushing car by inches.