Obviously, he and Ariel were two of the five presences, but that left three of whom he had no knowledge. One of the three had arrived just a few days before. The other two, apparently traveling together, had been here for a slightly longer period.

The only ways they could have gotten here were with another Key to Perihelion, if there was another one off the planet, or in spacecraft. Either way, they offered additional chances for Derec and Ariel to get away from Robot City. He stayed on the computer all evening, trying to find more information.

He also rigged the chemical processor to make a new boot. It didn’t match, being made of organic materials instead of synthetics, but it fit well enough.

He finally quit for the night when he felt his concentration slipping. After getting something else to eat from the chemical processor, he fell into bed. Ariel was still asleep.

Derec was exhausted, but as he lay in the dark, his mind was still racing. He kept reviewing his new knowledge over and over-Ariel Welsh, her disease, the duplication of the Key… and now, three more humans on Robot City-which might mean, possibly, some new ways to get off the planet. Finally, just before he drifted off to sleep, he heard Ariel leave her room and turn on the chemical processor. For tonight, at least, she was all right.

When Derec emerged for breakfast the next morning, clean and dressed, Ariel was working at the computer. He was hesitant to interrupt her there. However, she looked up when he turned on the chemical processor.

“Morning, Derec.” She smiled shyly. “Are you still mad at me?”

“No. I guess you had good reason to be upset.”

“I just felt so guilty and confused about everything. Especially keeping secrets from you, when you were wondering about the city and all. I’m really sorry.”

“I’m just glad you finally told me. In the long run, maybe my knowing that stuff will help us.”

“I saw the file you left on the console, the medical one. You were trying to help me, weren’t you?”

“Yeah. I’m afraid there wasn’t much about diseases, though. But did you see that we’re not alone?” He took his breakfast out of the processor and sat down next to her, his plate on his lap.

“Yes! I was just looking at the notation. Do you have any idea who they could be?”

“No, I don’t. As soon as I’ve finished eating, I’ll see if I can find any more information about them in the computer, but I’m not too optimistic. Until I get more streamlining done, this computer can know all kinds of things and not realize it, you might say.”

“This is such a strange place.” Ariel sighed. “When I left Aurora, I was looking for adventure as well as a cure. I got the adventure part, such as it is.”

“Like getting captured by that pirate, Aranimas?” Derec grinned. “When he got hold of me, I wasn’t looking for adventure at all.”

“We made a pretty good team, though, taking care of ourselves in that situation.”

“Don’t forget the rest of the team-Alpha, the robot I put together out of all those parts, and Wolruf.”

“That little alien. I wonder what happened to them.”

“Yeah.” He was quiet for a moment, thinking about them. When he and Ariel had used the Key, and as a result had arrived in Robot City, Alpha and Wolruf had been left behind.

“Wolruf could be so surprising. One minute, she seemed like a very shy, subservient little creature, and the next minute we were relying on her for our lives.”

“That’s true. And Alpha’s certainly unique, since I had to cobble him together out of random parts. Did I tell you he has a special arm? It’s made of a kind of cellular substance. I ordered him to move it as though it’s jointed like everyone else’s, but actually he can make it completely flexible, like a tentacle. I wonder where they are now.”

“We’ve never really talked about this, before, have we? About our being friends, I mean, and what we’ve done together.”

He looked up at her. She was more at ease than he had ever seen her. He, too, felt the difference. Somehow, he trusted her now, though for all he knew, she could be keeping other secrets. She didn’t act like she was.

“Derec, you’ve been very understanding. I appreciate it. Thank you.”

“Uh…” He gave just a hint of a shrug. “That’s okay. Now, let’s see if we can figure out how to get off the planet. “

Derec and Ariel took turns on the console all morning. This gave him a break every so often and gave her some practice. He sat looking over her shoulder as they tried to think up more questions to ask the computer.

“Derec, do you think the strangers that we’re looking for have been able to hide? Or disguise themselves?”

“Maybe, but I don’t see how. If they tried to hide, they’d still find robots everywhere in Robot City. They would have to stay inside someplace, and even then, they might be in a building that was scheduled for modification or tearing down by the robots.” He laughed. “That would give them a good shock.”

“And disguising themselves as robots might be a little difficult.” She turned, also laughing, to catch his eye.

“Or maybe we could get some scrap robot parts ourselves, and wear them around like ancient armor.” Derec shook his head, still grinning. “Especially those helmet-like heads.”

“Seriously, though. What could have happened to them?”

“Well, it’s possible that there are more sightings that have been lost in the central computer someplace. Otherwise, I don’t really have an answer.”

“I’ve asked about all the questions I can think of. I don’t know what else to do.”

“Let’s try another train of thought,” said Derec. “We don’t know who they are-but what are they coming here for? What do they want?”

“The Key!”

“That’s my guess. But other space traffic could come this way, even though we seem to be off the beaten track here. How about this: they knew Dr. Avery and came here to take over. Or what about your mother-could she have sent someone here to check on her investment?”

“I don’t believe my mother actually knows where Robot City is, or maybe even exactly what it is.”

“That narrows it to two possibilities I can think of. Either they’re travelers who arrived by chance, maybe for repairs or fuel, or they came for the Key and maybe to take over Robot City. Can you think of anything else?”

“Maybe Avery himself, if he isn’t dead. I doubt that, though. He’d be in his office running things, not allowing these chance sightings. But what are we going to do?”

“We’ll have to go out and look around for ourselves, I guess. Unless you have another suggestion.”

She shook her head.

“We’ll have to be careful, though, till we find out who they are and what they want. We’ve gotten used to a certain amount of security here with the robots, since they can’t hurt us, but now that’s changed.”

“Not as long as we have robots around us. Remember, they can’t stand by and allow us to come to harm, either. What about asking Avemus or one of the other Supervisors to help us find them?”

“Not right now. I don’t want to alert the Supervisors to our interest in getting the Key, and so far they’ve left us alone. Let’s start by going back to the Key Center. If we can get our hands on a key, we can just leave Robot City to fend for itself.”

This time they took standard transportation, even though it took them farther out of their way than the vacuum chute had. The subway tunnels were another development that had become feasible once the shapechanging had stopped. They were full of robots, going about their daily business, who could be questioned. Derec and Ariel went to the nearest tunnel stop and rode down the ramp.

Traffic in the tunnels took the form of a robot, or a human, standing on a meter-square platform, enclosed by a booth of transparent walls, with a small console that could be set for whatever stop the passenger wished. The platforms ran on tracks; some parts of the city had as many as fifteen parallel tracks. The tunnel computer, an offshoot of the central computer, did all the steering, and could shift platforms from one track to another in order to create the most efficient flow of traffic. Tunnel stops had additional siding loops for loading and unloading. The technology reminded Derec of the lift system he had seen on the asteroid where he had first encountered the Avery robots.