Lindsay put her foot down hard on the accelerator as the motorway approach road suddenly turned into the fast lane. No matter how often she drove along Glasgow's urban motorway, she could never accustom herself to its vagaries. It had to be the only motorway in the world where you entered and left in the fast lane! Her nationalistic friends were convinced it was all part of an evil English plot to reduce the Labour-voting Scottish population in hideous road accidents, but Lindsay preferred to believe in the Department of Transport's incompetence rather than conspiracy theory.

She flicked the switch that put her engine into overdrive and turned the heater up full. Thundering down the motorway betrayed every draught in the elderly car's hood. At least it wasn't too far from Glasgow to the women's prison near Stirling where Jackie was being held. Claire had pulled strings to arrange an early visit for Lindsay, who had been instructed to say she was working for Jim Carstairs, Jackie's lawyer.

Just after ten, Lindsay pulled off the motorway and drove down the quiet country roads that brought her to the prison gates. A fifteen-foot-high fence of spiked metal stakes was topped with barbed wire, stretching as far as the eye could see in both distances. The gate was equally forbidding. Lindsay parked her car in the visitors' car park opposite the gates and crossed over. She rang a bell by the gate, and a woman in prison officer's uniform emerged from a small gatehouse. She opened a panel in the gate. "Can I help you?" she asked pleasantly.

"Good morning," said Lindsay. "I've come to see Jackie Mitchell. Mr. Carstairs arranged the appointment."

"You're the woman from her lawyer's, are you? We were expecting you. Have you any identification?"

Lindsay produced her driving licence and a covering letter from Jim Carstairs which she'd collected en route. The officer examined them, then opened a small door set into the gate and indicated that Lindsay should enter. "Just walk up the path to the first building and through the doors marked reception. Someone there will sort you out."

Thanking her, Lindsay set off up the tarmac path. Her destination was a modern, three-storey block, like all the other buildings. Apart from the bars on the windows, it could have been a block of students' residences. The path was flanked by neat lawns. There was no one else in sight as Lindsay reached a pair of sturdy wooden doors with a black and white plaque that stated simply "Visitors' Reception." Lindsay tried the right-hand door, which opened on to a small room divided in two by a wide counter. On her side, there were several institutional plastic chairs. Behind the counter were two prison officers, whose conversation stopped abruptly as Lindsay entered.

Her bag was efficiently searched, then she was led through another door, down a cream-painted corridor lined with amateurish watercolours of the Stirlingshire hills, and finally through another door into a tiny interview room. The room had one large, barred window overlooking the lawns and a distant stand of mixed conifers. Its only furnishings were a small deal table and two plastic chairs. The vinyl floor was pocked with cigarette burns, doubtless as a result of the inadequate little tinfoil ashtray on the table. "Sit there," the officer said, pointing to the chair nearest the door. "You must not touch the prisoner," the officer said. "If you want to offer her a cigarette, you should place the packet and the lighter on the table and let her pick it up. Is that clear?"

Lindsay nodded and immediately lit up, leaving the packet on the table beside her lighter. She had smoked less than half the cigarette before the door opened and another officer brought Jackie in. If she hadn't been expecting her, Lindsay would never have recognised the woman she used to know. When Lindsay had first met Jackie, she had been cheerful and vivacious. Her shapely figure, bordering on the voluptuous, had always been immaculately turned out in the height of fashion. Her copper hair had been cut and styled regularly. She could never have been described as beautiful, but her milk-white skin and her pale green eyes, which had always reminded Lindsay disconcertingly of gooseberries, had been carefully made up to show her to her best advantage.

The woman who was moving across the room towards Lindsay looked like a grotesque caricature of that Jackie Mitchell. She had put on weight, and her pasty face looked bloated and puffy. Her hair had lost its shine and was tied back untidily with an elastic band. The prison-issue denim overalls made her figure look lumpy, with hips out of proportion to the rest of her. Her eyes looked dull, and there were dark bruises underneath them. She barely seemed to notice Lindsay's presence as she slumped into the chair and reached for the cigarettes.

"Hello, Jackie," Lindsay said quietly.

"Thanks for coming," Jackie said, not sounding particularly grateful. "Claire said she'd try to find you. I wish she'd been able to get you sooner."

"I'm sorry too," Lindsay said. "But at least I'm here now. I don't know what exactly I can achieve, but I'll do everything I can to get you out of here." There was an awkward pause.

"You do know I didn't do it, don't you?" Jackie suddenly demanded fiercely, challenging Lindsay with a defiant glare.

"If you'd been going to kill Alison, I don't think that's the way you'd have chosen," said Lindsay.

Jackie gave a harsh bark of laughter. "Damn right. If I'd killed Alison, I'd have made bloody sure I didn't get caught. She wasn't worth serving a life sentence for. But I don't have to tell you that. You know better than anyone what she was like, don't you?"

"I have very vivid memories of what Alison was like, yes."

"I know, I know. She told me she'd had you on her hook. Told me that's why you had to do a runner to London. Told me you were scared of what she could do to you. I thought to myself then that if she could put the frighteners on someone as tough as you, I didn't have a cat's chance." Lindsay listened, appalled, to Jackie's words.

"But that's not true," she protested. "I went to London because of Cordelia, not Alison. I'd finished with her long before I even met Cordelia. She was just trying to scare you, Jackie. I called her bluff, you see. I was the one that got away, and she didn't like that."

Jackie's face crumpled, and Lindsay thought she was on the point of tears. Instead, she crushed out her cigarette and lit another immediately. Lindsay noticed her nails were bitten to the quick. "The bitch," Jackie said bitterly, sucking the smoke deep into her lungs. "My God, she deserved to die."

"Want to tell me about it?"

"I still don't understand how it happened. I hadn't even thought about being unfaithful to Claire until I did so. I suppose we were in a bit of a rut, but it was a rut I liked. It was comfortable, it was home. Then Alison started planting her poison. It was all very subtle, just the odd sentence here and there, all calculated to make me start wondering if we were as solid as I thought." Jackie rubbed her eyes. "God, I was gullible."

Lindsay nodded. "She was good at that. I've seen her do it to other people."

"But I fell for it. And then I fell for Alison. We'd gone out for a meal one night after I'd been working at the Clarion. We got royally pissed, or at least I thought we did. Looking back on it, I think I got royally pissed and Alison stayed sober. We went back to her place, lights down low, Mary Coughlan on the stereo, another little drink. Next thing I know, we're undressing each other and it's hands everywhere. And that was that. I was hooked." Jackie stared bleakly at the wall, trapped by the memory.

"She was like a drug," Lindsay said, caught in the memory of her own affair. "I couldn't get enough of her. It was as if the act fueled the appetite."

"That's it, that's exactly it. Sex with Alison was like living your fantasies. In a funny kind of way, I was almost glad when Claire found out. I thought that her knowing would break the spell, that I'd be able to escape Alison. But it didn't work, did it? Even though she's dead, I'm still her prisoner."

"What actually happened that last afternoon?"

Jackie sighed. "I told Claire I was going to end it, and I went round there all fired up with determination. Alison opened the door to me stark naked, and it took all my strength not to dive straight into bed with her then and there. But I made myself go through with it. I told her what I had decided, that I wanted Claire, not her.

"First, she tried to be seductive and talk me out of it. But I managed to stay firm. Then she lost her cool. Or at least, she seemed to. She burst into loud sobs and told me how much I meant to her and how she couldn't let me go. I was shaken to the core. I had to keep reminding myself that it was Claire I loved. It wasn't easy to hang on to that, faced with Alison in floods of tears.

"Then, when she saw that wasn't going to work, she started to threaten me. She told me she'd tell Claire all sorts of lies - that we'd had a threesome with a man, that I'd gone out with her to a club and we'd picked up two men and had sex with them, that we'd been using cocaine to improve our sex life. Oh God, you wouldn't believe the filth she was coming out with! And she said she'd spread all this poison round the city, make sure that no one gave me any work." Jackie's voice cracked, and she lit another cigarette.

Lindsay nodded sympathetically. "I know exactly what you mean. She tried the same routine on me. But I just laughed at her. I didn't have a lover to lose at the time, and I knew she couldn't destroy me professionally without damaging herself. The gamble paid off for me. But if she'd tried that on when I'd actually been with someone I loved, I doubt that I'd have been able to be clear-headed about it. You mustn't put yourself down for falling for it."

Jackie shook her head. "I can't help it. I mean, if I'd just stopped to think about it for a minute, I would have realised that there was no reason on earth why Claire or anyone else should fall for her lies. But I didn't stop to think. I should have been stronger, Lindsay. Then I'd have been out of there an hour or more before she was killed. I'd have had an alibi. Instead, I caved in and went to bed with her. You know what disgusts me most about myself? I actually enjoyed it. After all she'd said and done, I still loved every minute of it. Isn't that sickening?"

Lindsay could think of nothing to say that would ease Jackie's self-disgust. "It's human," was all she managed. "What happened then?"

"Alison started shooing me out. She said her mother was coming to see her, and she didn't want me wandering round with a just-fucked look on my face. So I got up and dressed in a hurry. I suppose that's how I came to leave my scarf behind. Then I got out of there. I stood on the landing waiting for the lift, feeling like a complete shit. I didn't want to go home. I couldn't face telling Claire I'd been so weak. So I left the landing and started walking down the stairs, just to give myself a kind of breathing space. But my legs felt shaky, so I sat down and had a cigarette. Then I carried on downstairs, got into my car and drove home. Mrs. Maxwell says she saw me, but I didn't notice her. I was in too much of a state, I guess. The rest you know."

Lindsay had listened to Jackie's account with a growing sense of helplessness. There wasn't even a loose strand anywhere she could start picking at to unravel this mess. "Didn't you see anybody else at all?" she asked.

Jackie shook her head. "Not a soul. But to be honest, if a rugby scrum dressed in tutus had been dancing the can-can on the landing, I doubt if I'd have noticed," she added with a touch of fire. "I was out of it, Lindsay, completely out of it."

"Do you know who else Alison was sleeping with while she was seeing you?"

"I've no idea. Christ, Lindsay, you know how clever she was at keeping her secrets. She could have been screwing half of Glasgow, and I'd never have known," Jackie said with a swift flash of her old liveliness.

Lindsay sighed and helped herself to a cigarette. It wasn't just Jackie's body that had been coarsened by prison life. Lindsay remembered her as a precise user of language, unusual in the rough and tumble world of newspapers in that she seldom swore. Now she'd fit in comfortably on any ship's bridge, never mind a newsdesk. Lindsay gave a mental shrug and carried on with her fruitless questions. "Was there any evidence at all that didn't fit the picture?"

"Not really. But Jim will show you all there is to see. It's hopeless, isn't it? I don't know why I was pinning my hopes on you. There's nothing anyone can do, is there?" Jackie said despondently, the animation that had briefly illuminated her face departing as swiftly as it had come.

"It's not hopeless," Lindsay lied. "I've hardly started. I've got one or two ideas of my own to pursue. I know most of the lads on the Clarion. There must have been some gossip kicking around at the time. And looking at the evidence might give me a few ideas. It's amazing what a fresh eye can come up with. Don't give up, Jackie. Alison Maxwell screwed up too many lives when she was alive. I'm damned if I'm going to stand by and do nothing while she screws up yours from beyond the grave."

"Big words, Gordon," Lindsay muttered to herself as she drove away from the prison. "And how the hell are you going to deliver this time?" In spite of her sympathy for Jackie, Lindsay had been only too glad to get away from the depressing encounter, especially after it became clear to her that Jackie knew nothing of Claire's affair with Cordelia. That would be a pleasant surprise for her to come out to, Lindsay thought angrily. No home, no job, no lover.

Lindsay thrust the thought of Claire and Cordelia away and reviewed what Jackie had told her as she drove back to Glasgow. No leads there, she mused. But she still had one or two cards up her sleeve. And maybe Jim Carstairs could give her some pointers that would be worth chasing up.

Less than an hour after she had left the prison, Lindsay was ensconced in the lawyer's secretary's office, ploughing through a thick file of all the case papers relating to Alison's murder. The police statements were interesting, as much for what they did not contain. They had been led straight to Jackie because of a name tape stitched into her scarf. In Jackie's statement, she'd revealed that it was a scarf she'd had since schooldays, hence the presence of the faded tape. Once they had Jackie in custody, she'd been picked out of an identification parade with no hesitation by Alison's mother, who had passed out cold as soon as she saw the woman she believed to be her daughter's killer.

Because they were certain they had the murderer, and because they were convinced it was an open-and-shut case, the police had not pursued any other lines of enquiry with much vigour. Judging by the statements from Alison's friends and colleagues, the questioning had been superficial in the extreme. By the time the papers had been passed on to the Procurator Fiscal for his decision as to whether there was enough for a successful prosecution, the case against Jackie looked overwhelming. And there were no other obvious suspects.

There was only one tiny piece of evidence which did not actually confirm Jackie's guilt. On the bedside table there had been a high-ball glass containing the remains of a whisky and water. There was a smudged lip-print on the glass, and faint traces of fingerprints. Only one was clear enough for the forensic scientists to lift a usable print. But it did not match Jackie's prints in any respect. Nor did it belong to Alison. They had half of a thumbprint from the glass, and the owner of that print was still unknown. Three hours later, that was still the only discrepancy that Lindsay could find in the case against Jackie. With a deep sigh, she closed the file and asked to see Jim Carstairs.

Lindsay was shown into a comfortable office, whose size was disguised by the piles of books, files, and loose papers stacked everywhere. "Come in, come in," Carstairs greeted her. He was a tall, thin man in his early thirties, with narrow shoulders and bony wrists that stuck out of his fashionable double-breasted suit. "Sit down, sit down," he added. "Sorry about the mess. The joiners have been promising to put my shelves up for months now, but they never appear. Now, how did you get on with the case papers?"

"They were heavy going," Lindsay admitted. "And I have to say there's not much there to lend support to the theory of Jackie's innocence. Apart from one thing."

Carstairs nodded encouragingly. He reminded Lindsay of her Latin teacher, another ugly, skinny man who'd been nicknamed Plug because of his lack of physical charms. But he'd been a kind teacher, who had always managed to draw out even those most lacking in confidence. Feeling reassured, Lindsay went on. "The glass," she said. "It doesn't fit."

"Well spotted," Carstairs said with an air of genuine delight at her perspicacity.

"And the police don't seem to have bent over backwards to try to find out who the mysterious thumbprint belongs to," she went on.

"Good. Of course, I needn't tell you that pursuing that course of inquiry was virtually impossible for us. After all, I have no authority to go round fingerprinting people. With the whole population of Glasgow to go at, and no real suspects other than Jackie, we couldn't begin to unearth the owner of the print. If there had been someone else who had been an obvious suspect, we could have got their prints by some subterfuge, I suppose. But neither Claire nor I had the foggiest idea where to begin," he apologised. "However, from what I'm told, which squares with what I understand about fingerprinting techniques, it's likely that the print had been made that day. They certainly weren't the sort of residual prints that might have been left after the glass had been washed," he continued enthusiastically.

"Who did the police fingerprint?" Lindsay asked, mildly irritated by Carstairs' failure to pursue the one lead that he and Claire had to the real culprit. God preserve me from falling into the hands of lawyers, she thought to herself.

"No one, really. They had no evidence apart from the glass that anyone else had been there. No one else had been seen or heard. Mrs. Makaronas from the flat upstairs heard Jackie and Alison quarrelling, but that was all she admitted to having heard."

"Would that be Ruth Menzies? The gallery owner?" Lindsay interrupted.

"That's right. A friend of the dead woman. Retains her maiden name professionally. Not a very helpful witness from our point of view. Now, as I was saying, the only direct evidence was the glass, and they didn't fingerprint all her friends and associates. In fact, they didn't even look too hard for her friends and etceteras, as you'll probably have picked up from the case file."

Lindsay shook her head doubtfully. "It's not much to go at. But at least it's a start. I was beginning to wonder if we were all wrong, and that maybe Jackie had actually done it, in spite of everything my instincts tell me about her and about this crime."

Carstairs nodded. "I know what you mean. I think we've all felt that momentary doubt. Including Jackie. I think there have been moments when she's wondered if she suffered some kind of brainstorm. The only one who's never doubted her innocence is Claire. She really has kept the faith."

Pity she couldn't have managed faithful as well, thought Lindsay sourly. But she kept her thoughts to herself and got to her feet. "Right," she said. "I'm off in pursuit of the missing thumb. I can't promise that I'll be able to get to the bottom of this, you do realise that? The trail I'm trying to pick up is very stale. Getting people to remember what happened four months ago is a tall order. Especially if one of them has something to hide."

"I appreciate that," Carstairs said, showing her to the door. "But we owe it to Jackie to try, don't we?"

"I'll be in touch if I need anything," she said on her way out.

Lindsay kept her word to the lawyer sooner than she expected. For when she returned to Sophie's flat, she found two men waiting for her.

"Miss Gordon?" Inspector Ainslie of the Special Branch asked as he and his colleague fell into step beside her. "We'd like you to accompany us to the station. We've got one or two questions for you about Miss Campbell's burglary."