"Residents should not be alarmed," the Voice said in its even bass tones. "A temporary power failure affecting your level has now been rectified."

"Power failure!" A picture flashed through Dirk's mind, a picture of Challenge-sealed, windowless, totally contained Challenge-without power. He did not like the idea. "What's going on?"

"Please do not be alarmed," the Voice repeated, but the overhead lights gave the He to its words. They went out entirely, and for a brief second Gwen and Dirk stood in frighteningly total darkness.

"I think we had better leave," Gwen said when the lights came back on. She turned and slid open the wall panel and began to remove their bags. Dirk went to help her.

"Please do not panic," the Voice said. "For your own safety, I urge you to remain within your compartment. The situation is under control. Challenge has many built-in safeguards, as well as back-ups for every important system.",

They finished packing. Gwen went to the door. "Are you on secondary power now?" she asked.

"Levels one through fifty, 251 through 300, 351 through 451, and 501 through 550 are on secondary power at present," the Voice admitted. "This is no cause for alarm. Robotechs are repairing primary power as quickly as possible, and other standby systems exist in the unlikely event that secondary power should fail."

"I don't understand," Dirk said. "Why? What's the cause of the failures?"

"Please do not be alarmed," the Voice said.

"Dirk," Gwen said calmly. "Let's go." She went out, a bag in her right hand and her sensor pack slung over her left shoulder on a strap. Dirk picked up the other two bags and followed her out into the cobalt-blue corridors. They hurried toward the tubes, Gwen two steps ahead, the carpets swallowing the sounds of their footfalls.

"Residents who panic are more likely to harm themselves than those who remain within the safety of their own compartments during the duration of this small inconvenience," the Voice chided them.

"Tell us what's going on and we might reconsider," Dirk said. They did not stop or slow up.

"Emergency regulations are now in effect," the Voice said. "Warders have been dispatched to conduct you back to your own compartment. This is for your own protection. I repeat, warders have been dispatched to conduct you back to your own compartment. The norms of ai-Emerel prohibit…" The words abruptly began to slur, and the bass voice rose and squeaked and became a grating whine that clawed briefly at their ears. It ended in a sudden shuddering silence.

The lights went off.

Dirk stopped for an instant, then took two steps forward in the thick darkness and bumped into Gwen. "What?" he said. "Sorry."

"Quiet," Gwen whispered. She began to count off the seconds. At thirteen, the hanging globes at the cross corridors came on again. But the blue radiance was a dim ghost glow, barely enough to see by.

"Come on," Gwen said. She began walking again, more slowly this time, treading carefully in the blue gloom. The tubes were not far ahead.

When the walls spoke to them, the voice was not the Voice.

"This is a large city," it said, "yet it is not large enough to hide you, t'Larien. I am waiting in the lowest of the Emereli cellars, the fifty-second sublevel. The city is mine. Come to me, now, or all power will die around you, and in the darkness my teyn and I will come hunting."

Dirk recognized the speaker. He could hardly be mistaken. On Worlorn, or anywhere, it would not be easy to duplicate the twisted, rasping voice of Bretan Braith Lantry.

They stood in the shadowed corridor as if paralyzed. Gwen was a dim blue silhouette, her eyes black pits. Her mouth twitched at the corner, reminding Dirk horribly of Bretan and his twitch. "They found us," she said.

"Yes," Dirk said. Both of them were whispering, out of fear that Bretan Braith-like the displaced Voice of Challenge-would hear them if they spoke aloud. Dirk was acutely aware that speakers surrounded him, and ears as well, and maybe eyes-all invisible behind the carpeted walls.

"How?" said Gwen. "They couldn't have. It's impossible."

"They did. It must be possible. But what do we do now? Do I go to them? What's down on the fifty-second sublevel anyway?"

Gwen frowned. "I don't know. Challenge wasn't my city. I know the subsurface levels weren't residential, though."

"Machines," Dirk suggested. "Power. Life support."

"Computers," Gwen added, in a small hollow whisper.

Dirk set down the bags he was carrying. It seemed silly to cling tightly to clothing and possessions at this point. "They killed the Voice," he said.

"Maybe. If it can be killed. I thought it was a whole network of computers, scattered throughout the tower. I don't know. Maybe it was only one large installation."

"In any case they got the central brain, the nerve center, whatever. No more friendly advice from the walls. And Bretan can probably see us right now."

"No," Gwen said.

"Why not? The Voice could."

"Yes, maybe, though I don't think the Voice's sensing devices had to include visual sensors, by any means. I mean, it didn't need them. It had other senses, things humans don't have. That's not the point. The Voice was a supercomputer, built to handle billions of bits of information simultaneously. Bretan can't do that. No human can. Besides, the inputs weren't intended to make sense to him, or to you or to me. Only to the Voice. Even if Bretan is standing where he has access to all of the data the Voice was getting, it will mostly be meaningless gibberish to him, or it will flood by so fast as to be useless. Maybe a trained cyberneticist could make something out of it, though I doubt it. Not Bretan, though. Not unless he knows some secret we don't."

"He knew how to find us," Dirk said. "And he knew where the brain of Challenge was, and how to short-circuit it."

"I don't know how he found us," Gwen replied, "but. it was no great trick to get to the Voice. The lowest sublevel, Dirk! It was just a guess on his part, it had to be. Kavalars build their holdfasts deep into stone, and the lowest level is always the safest, the most secure. That's where they quarter the women, and other holdfast treasures."

Dirk was thoughtful. "Wait a minute. He can't know exactly where we are. Otherwise, why try to get us down to the basement, why threaten to hunt us?"

Gwen nodded.

"If he's in a computer center, though," Dirk continued, "we have to be careful. He might be able to find us."

"Some of the computers must still be functioning," Gwen said, glancing toward the dim blue globe a few meters away. "The city is still alive, more or less."

"Can he ask the Voice where we are? If he brings it back?"

"Maybe, but would it tell him? I don't think so. We're legal residents, unarmed, he's a dangerous intruder violating all the norms of ai-Emerel."

"He? You mean they. Chell is with him. Maybe others as well."

"A party of intruders, then."

"But there can't be more than-what? Twenty? Less? How could they take over a city this size?"

"Ai-Emerel is a world singularly without violence, Dirk. And this is a Festival world. I doubt that Challenge had many defenses. The warders…"

Dirk looked around suddenly. "Yes, warders. The Voice mentioned them. It was sending one for us." He almost expected to see something large and menacing wheel into sight from a cross corridor, as if on cue. But there was nothing. Shadows and cobalt globes and blue silence.

"We can't just stand here," Gwen said. She had stopped whispering. So had he. Both of them realized that if Bretan Braith and his fellows could hear every word they spoke, then they could surely be located in a dozen other ways as well. If so, their case was hopeless. Whispering was a wasted gesture. "The air-car is only two levels away," she said.