Lindsay fiddled with the radio tuning buttons again. She'd been parked across the street from the industrial unit that housed Watergaw films for the best part of an hour. So far, she'd grown irritated with one presenter's attempt at controversiality, bored with a magazine programme that seemed to cater for the prurience of people without a life of their own, and infuriated to discover a play she'd been listening to was the first of three episodes of a serial. Now she'd never know why Prunella had taken the Old English sheepdog to the archbishop's consecration. Giving up on talk radio, she settled for a station that played oldies with minimal chatter between records.

It was at times like this that she missed smoking. It was one of the few pastimes observers could indulge on a stakeout without having to take their eyes off the target. And of course, Lindsay realised with a shock, surveillance was something she had only ever done as a smoker. Since she'd quit, she'd been doing the kind of respectable job that didn't involve spying on complete strangers. It wasn't something she'd missed, especially on a baking afternoon in a car with no air conditioning. Already her whole body felt slick with sweat. Wondering why she'd let herself be talked into this, Lindsay rooted in her backpack for a tissue and wiped the perspiration from her palms again.

Just after four, the metal-sheathed side door opened and a woman appeared wearing a short, sleeveless dress and low-heeled Greek sandals with thongs that criss-crossed half-way up her calves. She was so short that it should have looked absurd, but slender enough for it to seem sexy. She had a boxy leather bag slung across her body, and she carried a small holdall that looked virtually empty. As she turned to check that the door had closed behind her, Lindsay caught a momentary glimpse of her face. "Bambi," she said aloud, turning the key in the ignition of the anonymous hatchback Helen had hired for her.

Stella crossed the car park, walking more briskly than Lindsay would have cared to in that heat. When she came level with a metallic green car, she slipped into the driver's door. She reversed out of her space and drove straight toward Lindsay. At the gate, Stella turned left and headed toward the tube station. Lindsay was caught facing the wrong direction and had to pull round hastily, amazed at the bus driver who let her out with a courteous wave. Maybe some things in London had changed for the better after all.

At the traffic light by the station, Lindsay was two cars behind Stella. As they swung across into Greenland Road, one car peeled off toward Kentish Town, leaving only one as a barrier. "Perfect," Lindsay muttered as they swung right into Bayham Street. The narrow roads were hot and dusty, choked with cars and delivery vans, motorbike couriers dicing with death as they slalomed through in the canyons between tall houses grimed with a century of metropolitan pollution. Stella clearly knew where she was going, zigzagging through back streets whose bleakness was unrelieved by the afternoon sun, weaving a course that took her behind St. Pancras and King's Cross stations, past dozens of struggling small businesses crammed under cheap flats.

A couple of times, it had been touch and go staying close to Stella through traffic that was heavier than Lindsay remembered it being when she had lived in the city. But she'd always managed to keep her in sight at the junctions where crucial decisions were taken. Once they'd cleared the Angel, they picked up speed on City Road, where the traffic was lighter and houses gave way to tall warehouses, old buildings where light industry had lodged since the bricks were first laid, offices nudged in among them down side streets. When they hit the big roundabout by Old Street tube, Lindsay was forced to sit on Stella's back bumper as the van between them peeled off into the middle lane. A quick left and a half right brought Lindsay on to unknown territory. All she knew was that she was heading in the general direction of the City, though she suspected they were going to skirt its eastern edge rather than penetrate the canyons of commerce themselves. Wherever they were headed, it wasn't home.

She wasn't happy with being slap bang in the middle of Stella's rear-view mirror, but she was torn between fear of losing her in unfamiliar streets and fear of being spotted as a tail. The decision was suddenly taken from her when a Porsche shrieked out of a side street, cutting in between her and Stella without even a wave of gratitude. "Pillock," Lindsay muttered, but her heart wasn't in it.

They carried on in the same direction, past streets she'd only ever heard of. Whitechapel Road from the Monopoly board. Cable Street, scene of the anti-Fascist riots of the thirties. Just when Lindsay was convinced the next junction must bring them hard up against the Thames, Stella swung left into a wide street. The Porsche roared off to the right, leaving Lindsay a gap to make up. As she turned, she saw the green car a few hundred yards down the road turning right into a narrow street. Swearing, Lindsay shot down to the turning and swung the car across the oncoming traffic in a blare of horns. She was in time to see Stella turn again. When she made it to the junction, Stella was gone, the green car somewhere in a maze of narrow streets. "Shit, shit, shit!" Lindsay yelled, smacking her hand hard against the steering wheel.

She pulled in to the kerb while she considered. If Stella had spotted her and deliberately shaken her off, there was no chance of catching her now. She'd be back on the main road and miles away within minutes. But she'd shown no signs of trying to shake off pursuit, so the odds were that she'd turned off the arterial road because she was near her destination. Logically, Lindsay decided, if she drove around the nearby streets, she'd come upon the Fiat.

As she drove slowly through the twisting narrow corridors of Wapping, she remembered the one and only time she had been here before. It had been a Saturday night, so cold her breath had puffed in clouds before her. She'd been on foot, one of hundreds of journalists and print workers who had come to demonstrate against the mass sackings of their colleagues by Rupert Murdoch's News International to make way for cheap new technology and the de-skilling of their craft. They'd come to protest but had ended up fleeing through the streets, driven ahead of mounted police gung-ho as Cossacks and with as much concern for those they pursued. The clatter of hoofs, the swish of police batons through the air, the screams of terror, and the plumes of steamy breath from the horses' nostrils were still lodged in Lindsay's brain, erupting occasionally as nightmares. Somewhere in the melee, Lindsay had become separated from her lover, Cordelia. They hadn't found each other until they'd both arrived home in the middle of the night. Terrified of losing each other in a more permanent way, they'd never gone back on that particular picket line.

Cruising that same patch in broad daylight was a different experience, even though the sun failed to penetrate as far as the pavement in quite a few streets. There was nothing threatening on this warm summer afternoon, Lindsay sighed. It was hard to imagine she was going to get instant access to the skeletons in Stella's cupboard by driving round Wapping in the sun. About to give up, Lindsay made one last turn into a street that was more of an alley, curving like a scimitar and dead-ending by the ornamental canal. Tucked in a vanway between warehouses was the green Punto.

Lindsay felt a mixture of irritation and satisfaction. If she'd lost Stella, she could have gone back to Helen empty-handed but virtuous. Now she was nailed to her tail for another sticky journey, more likely than not. She turned her car round and backed into a space right at the end of the cul-de-sac. It was on double yellows, but she couldn't imagine a traffic warden coming all the way down there on the off chance in heat like this.

She looked across at the building whose vanway held the Fiat. There was nothing to indicate who the tenants were or what they did. It was simply a blank box in dirty red brick with windows that indicated four floors above the ground-floor level, which had no windows at all. Time to take a chance, Lindsay decided. She got out of the car, leaving it unlocked in case she needed to make a quick getaway, and walked purposefully across the street. The building had a side entrance, a pair of heavy wooden doors at the top of three shallow concrete steps. Lindsay tugged the brass handles, relieved when one opened and admitted her into a small foyer. Ahead were more double doors, this time steel and reinforced glass. By an entryphone was a bank of etched metal plaques. Dessins Domingo was the tenant of the top floor. Underneath them were Bronzed Bodies - Sculptures, and Media Masters, followed by Heavenly Dolls, Stationary Cycles plc, and Gorton Engineering.

Lindsay made a quick note of the names, though she felt fairly sure she wouldn't be far wrong if she looked for Stella Piper at Media Masters. The only question was what Media Masters did, and what Stella was doing there. She walked back to the car and moved it to the street where the cul-de-sac emerged, finding a handy space facing in the direction Stella would logically take to get back to civilization as Lindsay knew it. She settled down for another wait. This time, she didn't have to hang around long. Within ten minutes, the Punto appeared at the junction and shot off into the Wapping labyrinth.

Once they were back on the main road, the route could not have been more simple. Tower Hill down to the Embankment, round the choked artery of Trafalgar Square and up Charing Cross Road, where the traffic was moving so slowly Lindsay could read the promotional posters in the bookshop windows. There were a couple of times when she thought she'd lost Stella at traffic lights, but the rush-hour traffic was so sluggish, she caught up on the next change. At Cambridge Circus, Stella slipped left into Shaftesbury Avenue, then turned right into the pulsating heart of Soho caf¨¦ society. She dog-legged her way through the streets until they reached a backwater where the flesh trade had not yet been ousted by fashion. Stella had slowed down to a crawl, obviously looking for a parking place. Behind Lindsay, a car pulled out and swung round a corner. Quickly, she reversed into the available space and jumped out in time to see Stella losing patience and bumping her car on to the pavement further down the street. She got out and headed back up the street in Lindsay's direction. Lindsay walked casually toward Stella on the opposite pavement, glad of the weather as an excuse for wraparound sunglasses that let her stare without being spotted.

Before she drew level with Lindsay, Stella turned into a shop. Instantly, Lindsay sprinted across the street and followed her in, realizing belatedly she had just walked into a sex shop. Videos for sale covered one wall, magazines another. Two cabinets in the middle of the floor held sex toys. A swift glance revealed dildos of proportions no one but a hardcore masochist could desire. With an inward shudder, Lindsay drifted toward the counter where Stella was standing, lips pursed in impatience, arms folded, and one sandalled foot tapping. Behind the counter was a youth so spectacularly lacking in physical charm that it was hardly surprising he'd chosen to work in a place that recognised the importance of fantasy. He had a phone clamped to one scarlet ear. The other stood out at ninety degrees to his shaven head. The tattooed fingers holding the phone read "shag." In your dreams, Lindsay thought derisively. Neither of them showed the slightest interest in Lindsay as she pretended to browse the videos.

"He's not answering," he said in a thickly adenoidal voice.

"I told him I was coming in this afternoon," Stella said peevishly.

"He never said."

"He must have told you where he was going."

"He never. He just said he had some business to sort." He replaced the phone under the counter. "D'you wanna come back later?"

"Not especially, no. Did your precious boss say when he'd be back?"

The youth shrugged nervously, one finger creeping reflexively toward a nostril. "He never tells me nothing. We're open till ten, though."

"I know you're open till ten," Stella said through gritted teeth. Lindsay had often read the expression, but she'd never seen anyone perform it before now. It was impressive, she had to admit. Stella hefted the holdall on to the counter. Where it had been almost empty before, it was now bulging, square corners pushing the fabric out in several places. "Have you got a box?" she demanded.

The youth looked as if gorm had followed couth out of his life a long time ago. "A box?" he echoed.

"A cardboard box? Big enough to hold the tapes I've got in here? I'll leave them for Keith, but I don't want to leave my bag behind, capisce?"

"Yeah, right." The youth disappeared through a bead curtain. Stella drummed her fingers on the counter top. Lindsay moved casually behind her to the opposite wall and started looking at magazines. Out of the corner of her eye, she could still see Stella. The youth emerged with a box about twice the size of the holdall. "This do?"

Stella didn't even bother to answer. She simply unzipped the bag and transferred about a dozen video tapes into the box. "When Keith shows his face, tell him Stella was here as promised. There's twelve samples in there. Six different films, each cut in two versions - one for America, one for Europe. Tell him to call me with his orders before Monday. Have you got that?" He nodded. "Repeat it back to me," she commanded.

"Stella came with the samples. Half a dozen films, American and European versions. Orders before Monday."

"You forgot the crucial bit," she snarled. "Tell him I get seriously pissed off with men who stand me up." She zipped the bag up again and stormed out. Lindsay couldn't see any point in following Stella any further. There was no need for overkill. Why bother hunting for a rifle when you already had an Exocet missile, Lindsay wondered.

She abandoned her pretense of studying the repulsive magazines and walked out of the shop. She felt like she needed a shower and a change of clothes, least of all because of the heat. But most of all, she needed a drink. Before she could do that, though, she had one more task to perform.

Glancing up and down the street, she saw a pair of telephone boxes on the corner. She walked up there and shut herself into one, seeing to her surprise that, like American pay phones, it took credit cards as well as money. "Nice one," she said appreciatively, swiping her card through the slot and calling directory inquiries. A voice worryingly like that of Margaret Thatcher gave her the number of Media Masters, and she keyed it in. "Media Masters, Julie-Anne speaking," a woman's voice chirruped.

Time to play a hunch. "Hey," Lindsay said, going for Californian. "My name is Catherine Parvenu, and I'm an independent filmmaker out of Los Angeles. Now, I'm in town for a few days, and I need some video facilities. Can you tell me, do you have editing suites for hire?"

"Well, yes, we do, but I'm afraid they're fully booked until early next week. I can put you on stand-by, if you like, but I can't make any promises."

"Gee, that's a pity. I really need something right away. Never mind, I've got a couple other numbers I can call. Tell me, do you also do video copying?"

"We do, madam. Single and multiple copies, U.S. and UK format, overnight express facilities available."

"And do you have spare capacity this week? I'm looking for fifty copies of a one hour VHS, U.S. format. Can you do that?"

"One moment, madam, let me check the diary... Yes, we can accommodate you. When will the master be available?"

"I have to get back to you on that. Thanks a lot, Julie-Anne, I'll be back to you tomorrow, okay?"

"We'll look forward to hearing from you."

"You have a nice day now." Lindsay intoned the West Coast mantra without obvious irony.

Now she'd confirmed her guess at what Media Masters did, she really needed that drink. Leaving the car where it was, she headed off into the heart of Soho and soon found a caf¨¦ bar where women who were enough like her for it to feel like home sat round a horseshoe-shaped bar drinking beer out of long-necked bottles. She ordered a Rolling Rock and savoured the moment's anticipation before the first swallow. She twirled the bottle, expecting to read through the drops of condensation the legend "Brewed in the glass-lined tanks of Old Latrobe." Instead, she discovered it was brewed in the tradition of Old Latrobe somewhere in the south of England. She sighed so hard the woman next to her asked what was wrong.

"You know that saying, 'You can never go home any more?' " she asked. The woman nodded, looking a little bemused. "Well, I think I just found out how true it is."