"The Braiths might be two levels away too," Dirk replied. "Even if they're not, we have to avoid the air-car. They have to know we've got one, and they'll be expecting us to run for it. Maybe that was why Bretan made his little speech, to flush us out into the air, where we'd be easy prey. His holdfast-brothers are probably out there waiting to laser us down." He paused, thoughtful. "But we can't just stay here, either."

"Not around our own compartment," she said. "The Voice knew where we were, and Bretan Braith might be able to find out. But we have to stay in the city; you're right about that."

"We hide, then," Dirk said. "Where?" Gwen shrugged. "Here, there, and everywhere. It's a big city, as Bretan Braith said."

Gwen quickly knelt and went through her bag, discarding all the cumbersome clothing but retaining her field supplies and sensor pack. Dirk put on the heavy greatcoat that Ruark had given him and abandoned everything else. They walked toward the outer concourse; Gwen was anxious to get as far from their compartment as possible, and neither of them was willing to risk using the tubes.

The lights above the wide concourse boulevard still burned bright and white, and the slidewalks were humming evenly; the corkscrew road seemed to have an independent power supply. "Up or down?" Dirk asked.

Gwen did not seem to hear; she was listening to something else. "Quiet," she said. Her mouth twitched. Above the steady hum of the slidewalks then Dirk heard the other noise, faint but unmistakable. A howl.

It came from the corridor behind them, Dirk was positive of that. It came like a chill breath from out of the warm blue stillness, and it seemed to hang in the air far longer than it should have. Dim, distant shouts followed close on its heels.

There was a short silence. Gwen and Dirk looked at each other and stood very still, listening. The howl came again, louder, more distinct, echoing a bit this time. It was a furious shriek of a howl, long and high pitched.

"Braith hounds," Gwen said, in a voice that was much steadier than it had any right to be.

Dirk remembered the beast he had encountered when he walked through the streets of Larteyn-the horse-sized dog that had snarled at bis approach, the creature with the hairless rat's face and the small red eyes. He looked down the corridor behind them with apprehension, but nothing moved in the cobalt shadows.

The sounds were growing louder, closer.

"Down," Gwen said. "And quickly."

Dirk needed no persuasion. They hurried to the median strip of the concourse, across the width of the silent boulevard, and got onto the first and slowest of the descending slidewalks. Then they began to move in, hopping from belt to belt until they were riding the swiftest of the descenders. Gwen unslung her field supplies and opened the packet, rummaging through the contents while Dirk stood above her, one hand resting on her shoulder, and watched the level numbers slide by, black sentinels mounted above the dusk-dark maws that led off into the interior corridors of Challenge. The numbers flashed past at regular intervals, growing steadily smaller.

They had just passed into the 490s when Gwen stood, holding a palm-sized rod of blue-black metal in her right hand. "Take off your clothes," she said.

"What?"

"Take off your clothes," she repeated. When Dirk only looked at her, she shook her head impatiently and tapped his chest with the point of the rod. "Null-scent," she told him. "Arkin and I use it in the wild. Spray ourselves before going out. It will kill the body scent for about four hours, and hopefully throw the hounds off the trail."

Dirk nodded and began to strip. When he was naked, Gwen made him stand with his legs far apart and his arms raised over his head. She touched one end of the metal rod, and from the other a fine gray mist issued, its soft touch tingling his bare skin. He felt cold and foolish and very vulnerable as she treated him, back and front, head to toe. Then she knelt and sprayed his clothing as well, inside and out, everything except the heavy greatcoat that Arkin had given him, which she carefully set to one side. When she was finished, Dirk dressed again-his clothes were dry and dusty with the ashen powder-while Gwen stripped in turn, and let him spray her.

"What about the coat?" he said while she got back into her clothes. She had treated everything: the sensor pack, the field supplies, her jade-and-silver armlet– everything except Arkin's patched brown greatcoat. Dirk nudged it with the toe of his boot.

Gwen picked it up and tossed it over the guardrail, onto the swiftly moving belt of an ascending slidewalk. They watched as it receded from them, out of sight. "You don't need it," Gwen said when the coat was gone. "Maybe it will lead the pack in the wrong direction. They're certain to have followed us as far as the concourse."

Dirk looked dubious. "Maybe," he said, with a glance at the inner wall. Level 472 came and went. "I think we should get off," he said suddenly. "Get away from the concourse."

Gwen looked at him, questioning.

"You said it yourself," he said. "Whoever is behind us will get at least as far as the concourse. If they've already started down, my coat won't fool them much. They'll see it sailing past, and laugh."

She smiled. "Conceded. But it was worth a try."

"So assume they're corning down after us…"

"We'll have built a good lead by this point," she interrupted. "They'll never get a pack of hounds onto a slidewalk, which means they'll be on foot."

"So? The concourse still isn't safe, Gwen. Look, that can't be Bretan up there, he's down in the sublevels. It probably isn't Chell either, is it?"

"No. A Kavalar hunts with his teyn. They do not split."

"I figured as much. So we've got one pair playing games with the power way below us, another pair at our backs. How many others are after us? Can you answer that?"

"No."

"I'd guess a few, at least; and even if it isn't so, we'd be better off to assume the worst and work from there. If there are other Braiths loose in the city, and if they're in contact with the hunters behind us, the ones above us will tell the others to close off the concourse."

Her eyes narrowed. "Maybe not. Hunting parties seldom work together. Each pair want the kill for themselves. Damn, but I wish I had a weapon!"

Dirk ignored her final comment. "We shouldn't take any chances," he said. Even as he said it, the bright lights above them began to flicker, fading down abruptly into a dun lingering grayness, and simultaneously the slidewalk beneath them jerked and began to slow. Gwen stumbled. Dirk caught her and held her in his arms. The slowest belt stopped first, then the one next to it, and finally the descender they were riding.

Gwen shivered and looked up at him, and Dirk hugged her more tightly, drawing desperately needed reassurance from the warmth and closeness of her body.

Below them-Dirk swore that the sound came from below them, from the direction the slidewalk had been taking them-a shrill scream rang briefly, and not so very far away.

Gwen pulled loose of him. They did not speak. They moved from belt to belt, across the shadowed, empty traffic lanes, toward the passage that led away from the dangerous concourse and into the corridors again. He glanced up at the numbers as they passed from gray dimness into blue: level 468. When the carpets swallowed their footsteps once again, they began to run, moving quickly down the first long corridor, then turning again and yet again, sometimes right and sometimes left, choosing at random the directions they took. They ran until both of them were short of breath, and then they paused and sank into the carpets beneath the light of a dusky bluish globe.

"What was it?" he said at last, when his breath returned to him.