"I'm not sure I-"

"Do you see what I'm saying? The investigator must always allow for this. The older we grow, the louder their voices, the more inarticulate they are." She made no further attempt to reply, so he said, "At least I don't hear them in this datapipe, that's a blessing," and then asked her to run the nanosurveillance from Straint Street, which she seemed relieved to do. After a few minutes following the life of the bar, he shook his head.

"Is this all that happened overnight?"

"Three or four a.m., the system went down again. There's some footage but it's not informative."

"I can believe that," Aschemann said.

"We should have put people in."

"Who would we use? This woman knows everyone who drinks at her bar. She's no fool, even if Vic is." Liv Hula stood motionless at the zinc counter; she leaned her elbows on the zinc counter. The footage jumped, and she leaned on the zinc counter again. She stared emptily ahead. She looked tired. "Switch this off, for God's sake."

Aschemann brushed at the sandy soles of his feet as if this action might clarify his life, or at least connect him to it. Two hours' sleep in an armchair had given him kidney pain, but it couldn't explain the feeling that something was approaching him, racing towards him from what part of his past he couldn't even guess. It couldn't explain why his hands were so stiff, as if he'd been clenching them tightly in his sleep. Only the dogs could explain that. "At least we know where they're going," he said. "We have an embarrassment of confirmation on that." Just before he closed the dial-up, so that the assistant would have no time to reply, he said, "By the way, did you enjoy that sleep of yours you had in the twink-tank?"

"Watch out for the dogs you hear."

Aschemann took his kidneys to the toilet, chuckling. "One day I'll give that tank a try," he promised himself.

"How will we know we're in there?"

Vic Serotonin stopped to allow his client to catch up. "Sometimes you don't," he said carelessly.

The event-the fall to earth, whatever you described it as-had taken place a generation or more ago, in the city's old industrial quarter, the warren of factories, warehouses, docks and ship canals which at that time connected Saudade to the ocean. Commerce had ended instantly, but its characteristic architecture remained as a fringe about half a kilometre deep, a maze of empty buildings with collapsing corrugated roofs and broken drainpipes, their iron window frames bashed in and emptied of glass. A mile or two past Liv Hula's bar, Straint narrowed to a lane; the cobbled cross-streets became little more than industrial alleys, pitted and rutted, littered with lengths of discarded cable and balks of timber. Everything smelled of rust and precursor chemicals. The blue enamelled signs on the street corners had long since corroded into unintelligibility. Elizabeth Kielar studied them and shivered.

"I'll know," she said.

"Then why ask me?"

"I'll feel it."

"All that happened last time," he reminded her patiently, "is you lost your nerve." The only reply she offered was an angry look; as if he were the unpredictable one, the one both of them had to be careful not to trust.

Over the years, Vic had given the question more thought than his tone implied. You knew you had entered the aureole when the weather changed, that was his view. Turn a corner between two factory yards in winter: sunlight would be falling into the well of the street while insects described fast, wavering trajectories from the brassy light into the darkness of the buildings. If it was sunny in Saudade, patches of fog drifted through the aureole. Or the wind would, as now, pile up a few cold, soft short-lived flakes of snow in the gutters. Whatever else happened, the shadows struck at absurd angles for the time of year, as if geography was remembering something else. "The lines of distinction aren't sharp," Vic concluded. You had to use your intuition as to when something like that became important.

"When the Kefahuchi Tract first fell to earth, they tried to build permanent controls. Walls, ditches, concrete blocks. But that stuff would be absorbed overnight." Something went wrong with the air, and next morning your border post had gone and you were looking across a fifty-yard waste lot covered in cheat weed and cracked concrete, at what appeared to be a huge, motionless, empty fairground in the rain. "Now they have a more relaxed attitude. Take the wire up every so often, put it down somewhere else: they call it 'soft containment.' " Still trying to explain himself, and thinking of the complexities of his relationship with Emil Bonaventure too, Vic added, "Even in the aureole you need luck. I'm not one of those people who believe they'll have street light in there by next Wednesday."

"Do any of you understand anything at all?" she said angrily. "Why do you all act as if you know something when you don't?"

"This area's thick with police. So try to keep up."

Twenty minutes later it was full dawn, and the first patrol of the day had caught up with them. Vic hurried Elizabeth through the nearest door and into a derelict warehouse-puddles, ripped-up concrete and foul earth, holes that gaped down into cellars and sewers, everything of worth stripped out long ago-where he pushed her to the floor and put his hand across her mouth. Elizabeth stared up at him in a kind of puzzled supplication, as if she didn't understand why humiliation should be part of this search for her own nature, while matt-grey Site Crime vehicles forced themselves down the narrow accessway outside, repeatedly occluding the light then allowing it to splash in again rich with steam cooked out of the standing water by the waste heat of the nuclear engines. The air shuddered with the din of it; above that, you could hear the faint realtime shouts of the foot police coordinating their sweep through the buildings.

"They're not looking for us!" Vic shouted into Elizabeth Kielar's ear. Nevertheless he made her lie there, listening, until long after the engines and the shouts had passed. Then they left, Elizabeth brushing irritably at her clothes. After that it was more of the same, rusting tracks, flooded rocket-docks with vast discarded machinery visible just beneath the surface of water stinking of the sea but so glamorised by exotic radiochemicals it would glow faintly in the dark. They made good time, and Vic Serotonin was pleased by the professional way things were falling out for once. But as they passed, everything-each alley and abandoned wharf, each collapsed or melted gantry, even the Site Crime patrols-seemed to settle, shift and morph indiscernibly into something else. The aureole was all around, like a wave propagated through everything. Everything was up for grabs. Half an hour later, when rain caught them at the edge of the site itself-a shower which slanted in, mercurial against the direction of the light, to pass within minutes-you couldn't, as Vic said, be sure where it came from, or how. Though on the face of it things looked simple enough.

Independent of the patrols, Lens Aschemann's pink Cadillac nosed its way down the pot-holed alleys, waited at each junction, then, accelerating briefly but wildly, left the road and bumped its way through the tall weeds of a concrete lot as if its driver had lost control of the clutch. With the detective himself at the wheel, the car's character changed. It became like a big, blunt animal, some species adapted neither for stealth nor pursuit but which, despite Darwinian constraints, had decided to learn them both.

Aschemann drove as if he couldn't see well, gripping the wheel tightly and thrusting his face close to the windshield, while his assistant suffered in the passenger seat, steadying herself with both hands and offering him an expression of open hostility.