Covers blown: to the unsuspecting passer-by, McIlvanney's characters appear confident and self-assured - until he delves into their innermost insecurities.

"At least my sense of men isn't. Like you, Kate. Dark pasts and romantic figures wrapped in mystery. Like a bloody opera-cloak. What're you waiting for? To meet Byron in Tesco's? He's dead. Long time dead. Look at them."

She indicated the young men at the bar. Kate followed her nodding head. She saw, first of all, the living representation of a thought she had often had: the physical variety of people is amazing. Wasn't it incredible that, with all the people there were in the world, you couldn't find two exactly the same? Even identical twins weren't really identical. The term didn't describe the reality, just the carelessness with which people observed the reality. And beyond a category like that, all was blatant and mind-blowing difference.

What life managed to do with limited materials was astounding. After all, how many different shapes could you give to something as basic as a nose? A bone, a lump of skin and two breathing holes. It wasn't exactly, you would have thought, the stuff of infinite variation. How many eye-colours could you get? Not a lot, and you weren't allowed to have different colours within any one iris. You couldn't, for example, have striped eyes. That might have helped to vary things a bit. And mouths. Two soft folds of flesh around a set of teeth or the lack of them, as the case may be. It really was amazing.

But that was what was wrong with cloning. People were always discussing the ethics of it. It didn't seem to her it was so much a matter of ethics as a matter of the nature of the experience. The whole nature of life, it seemed to her, moved towards difference, unique individuality. At least among people that was true. In a sense, life never repeated itself. Cloning was a precise, deliberate repetition. Cloning was anti-life.

Yet, watching the men at the bar, she was forced to wonder if cloning had been invented before Dolly had come along. For all their immediately obvious physical differences, these men seemed determined to pretend they were all one another. It wasn't just their clothes. The behaviour of each was like an echo of everybody else in the group. They had the same self-assurance, the same way of glancing arrogantly round the pub. They laughed like a convention of mimics. They were trying, she decided, to clone themselves psychologically.

It was sad. It was sad because it couldn't be true. There had to be some who felt a little insecurity. Maybe one didn't feel tough at all. Maybe one was afraid of spiders. Maybe one was even still a virgin. But you couldn't have guessed it.

It wasn't that she would have expected them to declare such things publicly. She didn't expect them to walk about with placards round their necks. Fragile - Handle with Care. Arachnaphobics Anonymous. Vagina might as well be a state in America for all I know about it. (That would have to be a sandwich-board, she supposed.) But she would have hoped the truth of themselves might be honestly, if obliquely, expressed in the way they acted towards others. Otherwise the most interesting aspects of themselves, the places where they really lived, were being denied all the time. So how could you hope ever really to meet them or, perhaps more importantly, allow them to meet you?

With these men, she didn't even want to try. They were all acting in close harmony, like a repertory company that had been together a long time. You were allowed to watch but they were the only ones who knew the plot. It was as if only they were natives here. Everybody else was just a tourist. She certainly felt like one.

"You see what I'm saying?" Jacqui was saying. "Just look at them. Romance? They think that's a long run for their team in the Cup. Don't waste your time looking for more than sex with them. They can only relate to you from the waist down. They look round the women in this pub, all they see is a lot of convenient spaces. Somewhere they can park their amazing equipment. Till the urge passes. And they can get on with what really matters again. Mainly beer with the boys and football matches. The rest is patter. Just the money in the meter that lets you stay there till you get your business done."

Kate winced. Some suspicion in her was worried that Jacqui was right. She didn't want her to be right but almost envied her for her certainty. At least it made her connect directly with the world around her, even if she did it rather abrasively. At least she was dynamic.

She seemed strong. Kate saw her as a kind of Boudicca figure. She drove through situations and her chariot wheels had blades on them, very sharp blades. So what if some people were hurt? It was mainly men she did the damage to and, post Kevin, she saw them as her enemies. At least she got where she was going. Didn't she? Kate always felt that she wasn't going anywhere. She was hanging about in the anteroom to her own life. If Jacqui was Boudicca, she was the Lady of Shalott. Weaving fancies inside herself and hardly daring to venture out into where things actually happened. Catching echoes of what it might be like.

And Jacqui was honest - often brutally honest, but honest. She wasn't. But to be honest you had to know what you thought about things. She didn't. Maybe that was why she accepted so many situations without reacting to them in the way she really wanted to. She hesitated too much. At school she had been the type of pupil who knows the answers but is afraid to put up her hand in case she is wrong and makes a fool of herself. She would have liked to be able to run home, check it out in the World of Knowledge book her father had bought and run back into the classroom with her hand up. She was the type, except with Alison and Jacqui, who was likely to listen to nonsense or swallow a mild insult and postpone a reaction until she had gone back to her room and reprocessed the entire occasion in her head. She always thought exactly what she should have said when there was no one there to say it to.

It was a kind of lying, not having the nerve to own up to the truth of where you were. It was a condition that had become more serious recently. It no longer applied only in incidental moments. It had taken up permanent residence in one particular area of her life. She could still hardly believe that she had lied to Jacqui and Alison about not being a virgin.

That was one of the problems with lying. You spent so much effort sustaining the lie and elaborating on it that you almost began to believe it. There were times, remembering real situations, like the one where she had had her pants off, when she could almost convince herself that what had happened was really a kind of sexual intercourse. She had to remind herself that it wasn't. She was the only supposedly sexually experienced woman she knew with her hymen still intact. At least, she assumed it was. If it wasn't, and her father insisted the culprit made an honest woman of her, she could probably look forward to marrying a bicycle.

But now she was trapped in the pretence. She knew that in any future conversations with Jacqui and Alison she might have to wheel in another imaginary lover. She had even thought of a couple of names. It was getting ridiculous. There was only one way to stop it: do it for real.

That wasn't the only reason she wanted shot of her virginity. It was a total embarrassment, like a pimple that never burst. It was so unmodern. She felt she might as well be going about in a bustle and having the vapours. She had to do something. She didn't know what but she had the vague idea that if she kept putting herself in promising situations it might happen to her before she could stop it. That was one reason she wanted to go to Willowvale. At least it would offer possibilities. A lot of men and a lot of bedrooms. Like her father's lotto card. Permutations there. But she needed Jacqui to go with her. It might give her the nerve to put herself about a bit more. It would open up the possibilities.

She noticed Jacqui and Alison exchange a glance she didn't understand. Jacqui seemed to become more thoughtful. Kate took it up as a hopeful sign. Perhaps she was considering David Cudlipp ...

...who was standing in his flat looking through the window down into the street, where one teenager was pushing another along in a supermarket trolley. Both seemed to be shouting some incomprehensible challenge to the street's residents. David drew back from the window a little in case he became the focus of their marauding arrogance. He remembered a thrown stone coming through the window about a year ago, for no other reason he could see than that the room was lit, with the curtains undrawn, and must have looked like a warm and pleasant place.

We've lost the streets, he thought, as he watched the two careen out of sight, bellowing like berserkers. The propriety of home no longer extends outside to walk the pavements sedately. The roughness of the roads invades the house, estranging us from each other within our own walls. Was that really his wife sitting on a chair and using a magazine she wasn't interested in like a stage prop?

"But what difference does it make? The room will still be taken. It's just that it'll become a single instead of a double. At least, I hope so."

"My own work has fallen behind in the library. I have to go in. Anyway, it's not as if I have any significant contribution to make. I'd just be a spectator."

"Listen," Jacqui said. "Vikki Kane could really look something special. She's got a lovely figure. Good bones. It's just the clothes she wears."

The idea of Vikki Kane gave Kate comfort. There was somebody else who didn't seem to belong in a modern context, so demure and reserved. She was so uncertain of herself it was hard to believe she was in her thirties. Maybe she wasn't the only Lady of Shalott, Kate thought, as she held in her mind the image of Vikki Kane ...

The white Lycra top and the black jeans looked good on her. The shop assistant had approved in the passing, saying the jeans made her look like one of those photographs where they've painted an outfit on somebody. "Know what Ah mean. Robbie Williams did it. All he wore was his underpants. And somebody had painted blue jeans on 'im."

The Lycra moulded itself to her breasts. They had hardly sagged at all. Maybe that was one advantage of having had only one child. Her bum looked firm in the jeans. Maybe her half-hearted visits to the gym, before she abandoned them two or three months ago, had done some good after all. Maybe it was the supportiveness of the cloth. It wasn't just that clothes could accentuate your good points and minimise the bad ones. Used carefully, they could amount to a kind of temporary cosmetic surgery. These jeans not only made her look more attractively tensile from the back, they also made it hard to imagine the cellulite underneath. Still, if this weekend fulfilled the promise she saw in it, she might have to take them off in company. Love me, love my cellulite. But perhaps by then the shadowy, faceless man would be too preoccupied to notice.

The thought returned her to the glass of white wine on the dressing table. She took another sip, fully aware of what she was doing. She was keeping her recently acquired sense of abandon topped up. She was grateful now that she had hardly ever drunk. It meant that it didn't take too much to shift her mood from brooding to carefree. There must be a lot of bottles of self-confidence she could take before any physical damage caught up with her. Whatever she died of, it was unlikely to be cirrhosis of the liver, she thought bitterly.

The idea released her from any self-criticism she might have felt in sitting here, watching herself in the dressing-table mirror as she took the wine. She toasted herself in the glass. If she was going to free herself from dead behaviour, she would have to uncork a few more bottles in the process.

Extracted from Weekend by William McIlvanney, to be published by Sceptre on August 10 at £16.99. Copyright © 2006 William McIlvanney. To order your copy at the special price of £14.49 inc P&P please call 0870 7552122 and quote offer reference BSH313 or send a cheque made payable to 'Bookshop Partnership Ltd' to Weekend, Ref BSH313, PO Box 104, Ludlow, SY8 1YB. Please allow up to 28 days for delivery.

IT'S more than 10 years since William McIlvanney's last novel, The Kiln. That book, and his much earlier Docherty, are two of the best novels of the last half-century. I almost wrote "two of the best Scottish novels", but the defensive qualification is unnecessary: two of the best will do.

Now, long-awaited, comes Weekend, and it is every bit as good. At first it seems very different from anything McIlvanney has done before, and that itself is unusual for a writer who is 70 this year. Yet there are reflective, ruminative passages in The Kiln that now seem to point towards this new novel.

The book has an epigraph: "Ladies and gentlemen, we've been sphinxed but don't let it spoil your weekend." It's very much to the point. Life goes wrong, we make a mess of things in so many ways, but it's our duty to go on living, to try to make sense of things, even to make redress. Late in the novel, one character turns to Conrad's Heart Of Darkness, and to a passage she has underlined: "Droll thing life is - that mysterious arrangement of merciless logic for a futile purpose. The most you can hope from it is some knowledge of yourself - that comes too late - a crop of unextinguishable regrets."

The novel is deeply serious, but never solemn, lit up by humour and characteristic sparks of epigrammatic wit. It's about courage in the face of failure and disappointment, about the necessity of keeping on going.

If that sounds bleak, the bleakness is redeemed by the author's sympathy, and by the lightness with which he treats the discovery of first love by two of the students. And everything in the novel is illuminated by the play of a subtle, sceptical and yet affirmative intelligence.

Weekend, one presumes, has been years in the writing; and there is scarcely a sentence that hasn't been pondered and mulled over. McIlvanney is a moralist as well as an artist, and this remarkable book is the fine fruit of a long engagement with what it means to be human and the question of how best we live our lives, of how we justify, obscurely and uncertainly, our existence.

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