Stunned, surprised, Caliban shut down the map display system. The bright colors and symbols of the map faded from his vision, and he found himself once again standing in the darkness, alone on an empty pathway in a quiet residential district.

Whywas there no information about that building? Perhaps he should go back there, examine the place firsthand. He of course had a perfect, detailed memory of what he had seen there, and no doubt he could work his way back through those memories for information. But he had not been looking for anything when he awakened, had not even been fully aware that he should have known more than he did. If he went back, he would learn more.

He turned around, was about to head back the way he had come, toward the lab. But then he stopped. Wait a moment. There was another factor. One he had not considered yet. He recalled that first moment of awakening, the sight of the woman unconscious at his feet, the blood pooling about her head. The cross-index system of his datastore flitted through a whole series of things even as he thought about that moment.

And it settled at a quotation from the Legal Code that leaving the scene of a crime before being interviewed by the police was itself a crime. His mind flittered through all the datastore had to say about the Legal Code, the concept of crime, and the idea of punishment and rehabilitation. All of it seemed to relate to humans, but it was not a great leap of reasoning to assume that committing a criminal act could mean trouble for a robot as well.

No, he could not go back there.

Wait a moment. Were there other blanks on the map? Other places where detail was limited in some way? Perhaps other places with limited information on the datastore would have something in common with the building he had left. Perhaps examining one ofthem would offer some clue; perhaps some thought or image would stimulate the datastore to offer some sort of information that could tell him about himself.

Caliban looked about the area and decided it would be best to get off the pathway while he was examining the map. He stepped off the path and walked a short way, until he found a slight depression in the rolling landscape. He sat down in it, reasonably sure he could not be seen from the path.

He returned his attention to the datastore map. At first, his mind cast back and forth across the map in random, swooping passes, trying to cover as much ground as quickly as possible while still keeping track of any building or place that seemed suspiciously blank. Then he resolved to quarter the whole city and go block by block, in an orderly manner. Perhaps there was something he could learn from the pattern of blanked places, something he could discern only when he had located them all.

The map of the city had definite edges to it, precise boundaries beyond which was nothingness. Caliban’s knowledge of the world, the universe, stopped at those borders. For a moment, Caliban toyed with the idea of venturing to the closest of those boundaries, just to see what it was like. He imagined himself standing on the edge of the world, looking down into nothingness. The idea was exciting and disturbing.

But no. It would not do to get sidetracked. First he must get answers about himself and about what had happened at the building where he had awakened. After those two mysteries were resolved, he could take the time to indulge his idle curiosity.

He set to work at the southern edge of the map and began to work across it methodically, examining a strip from east to west, then moving northward to examine the next strip, west to east.

And then he found it. Not far from the southern edge of the map was a great void, an emptiness a thousand times, ten thousand times larger than the blank, unmarked building in which he had awakened. But this was no area without detailed markings. This was emptiness, the absence of all things. No land, no water, no buildings, no roads. There was nothing there at all.

He wondered if the map was reporting literal truth. What could such a void look like in real life? What would cause it? His curiosity, his eagerness to see this place, was all but uncontrollable. But he held firm to his plan. He must examine the whole city, absorb the whole of the datastore map into his active memory. There could be other voids as well, equally significant. He held to his search pattern, moving south to north, shuttling east to west, west to east.

It took the better part of an hour, but at last Caliban had worked his way across the whole of the map of Hades. Yes, there were other voids, but none of them were even a fraction as large as the first he had found. Yes, there were other unmarked, unlabeled buildings, but he could not see any obvious pattern, no relation to the features on the rest of the map, that told him anything meaningful, or anything at all.

There was nothing left for it but to go and look. Now there was no reason to resist the temptation to see what the great void looked like. Caliban stood up and walked back to the field, using his infrared vision to move easily through the darkness.

The site of the void was a good distance across the city, and the first hints of dawn were lighting the east as he traveled through the semi-arid, half-populated expanses of Hades, imagining what a great emptiness would look like.

But what he saw when he got there was no blank on the map. As the dawn broke full over the horizon, Caliban stood at the edge of where the map said there was only emptiness.

What Caliban saw was a lively oasis in the midst of the fading city. He stood at the edge of a broad and verdant park, dotted stands of trees, great lawns, spraying fountains.

Small pavilions dotted the landscape and seemed to give access to underground facilities, judging by the people going in and out. Caliban walked along the low stone wall that formed the perimeter of the park, until he came to the entrance.

Settlertown,a sign said. Caliban stared at it in confusion. Another mystery. He had no idea what Settlers were, or why they should have their own town. He called to the datastore, but it had no information on any such term.

For some reason, all information regarding both his origin point and this place had been deleted from his datastore.

But why would anyone do that?

DARKNESS had passed, and dawn had come over the horizon, and the morning was well begun. Alvar Kresh paced the room, listening to the routine words of the routine interrogation of yet another routine coworker, one Jomaine Terach. Terach wasn’t normally up and at the lab by this hour, but he lived quite near the lab and all the commotion had wakened him. He had wandered over to see what was going on-or so he claimed. Police officers throughout history had been a little slow to believe witnesses who explained trifles such as coming to work with such elaboration-and Kresh was tempted to uphold that tradition in the present instance. It would be wise to treat everyone as a suspect just at the moment.

Kresh let Donald do most of the work. This night had been a long, hard journey through the darkness to the day. Crime scenes could be grueling.

They had taken over the duty office for the purpose of doing the intake interrogations, taking each worker as he or she arrived. The duty office was designed to accommodate an overnight stay, in case an experiment ran all night. The office featured a large and rather comfortable-looking bed, much better than the miserable cot in the duty room at Sheriff’s HQ. After a sleepless night, it looked more than slightly inviting.

“Tonya Welton claims that Fredda Leving was-is-working; for her. Is that true?” Donald asked.

“Absolutely not,” Jomaine Terach said, yawning mightily. “Fredda Leving has never worked for anyone but herself in her life, and she isn’t likely to start in by oiling up to the high and mighty Queen of the Settlers.” He yawned again. “My God, it’s early. Have you been at it since the attack?”