She is quite aware how old-fashioned it sounds. West will have defenders by the thousand. How can we know the horrors of the Nazis, those defenders will say, if our artists are forbidden to bring them to life for us? Paul West is not a devil but a hero: he has ventured into the labyrinth of Europe 's past and faced down the Minotaur and returned to tell his tale.

What can she say in reply? That it would have been better if our hero had stayed at home, or at least had kept his exploits to himself? In times when artists clutch to themselves what few tatters of dignity they have left, what gratitude will that kind of answer bring her among fellow writers? She has let us down, they will say. Elizabeth Costello has turned into old Mother Grundy.

She wishes she had The Very Rich Hours of Count von Stauffenberg with her. Could she merely glance again at those pages, brush her eyes across them, all her doubts would vanish, she is sure, the pages where West gives the hangman, the butcher – she has forgotten his name but cannot forget his hands, just as no doubt his victims carried the memory of those hands, fumbling at their throats, with them into eternity – where he gives the butcher a voice, allowing him his coarse, his worse than coarse, his unspeakable gibes at the shivering old men he is about to kill, gibes about how their bodies are going to betray them as they buck and dance at the end of the rope. It is terrible, terrible beyond words: terrible that such a man should have existed, even more terrible that he should be hauled out of the grave when we thought he was safely dead.

Obscene. That is the word, a word of contested etymology, that she must hold on to as talisman. She chooses to believe that obscene means off-stage. To save our humanity, certain things that we may want to see (may want to see because we are human!) must remain off-stage. Paul West has written an obscene book, he has shown what ought not to be shown. That must be the thread of her talk when she faces the crowd, that she must not let go of.

She falls asleep at the writing table, fully dressed, with her head on her arms. At seven the alarm rings. Groggy, exhausted, she does what she can to fix her face and takes the funny little elevator down to the lobby. 'Has Mr West checked in yet?' she asks the boy at the desk, the same boy.

'Mr West…Yes, Mr West is in room 311.'

The sun is streaming through the windows of the breakfast room. She helps herself to coffee and a croissant, finds a seat near a window, surveys the half-dozen other early birds. Might the stocky man with the glasses reading the newspaper be West? He does not look like the photograph on the book jacket, but that proves nothing. Should she go across and ask? 'Mr West, how do you do, I am Elizabeth Costello and I have a complicated statement to make, if you will hear me out. It concerns you and your dealings with the devil.' How would she feel if some stranger did that to her while she was at breakfast?

She gets up, picks her way among the tables, taking the long route to the buffet. The paper the man is reading is Dutch, the Volkskrant. There is dandruff on the collar of his jacket. He glances up over his spectacles. A placid, ordinary face. He could be anyone: a textiles salesman, a professor of Sanskrit. He could equally be Satan in one of his disguises. She hesitates, passes on.

The Dutch paper, the dandruff… Not that Paul West might not read Dutch, not that Paul West might not have dandruff. But if she is going to set herself up as an expert on evil, ought she not be able to sniff evil out? What does evil smell like? Sulphur?

Brimstone? Zyklon B? Or has evil become colourless and odourless, like so much of the rest of the moral world?

At eight thirty Badings calls for her. Together he and she stroll the few blocks to the theatre where the conference is to take place. In the auditorium he points to a man sitting by himself in the back row. 'Paul West,' says Badings. 'Would you like me to introduce you?'

Though it is not the man she saw at breakfast, the two are not unalike in build, even in looks.

'Later perhaps,' she murmurs.

Badings excuses himself, goes off to attend to business. Still some twenty minutes before the session begins. She crosses the auditorium. 'Mr West?' she says, as pleasantly as she can. Years since she last employed what might be called feminine wiles, but if wiles will do the trick then she will use them. 'Might I speak to you for a moment?'

West, the real West, glances up from what he is reading, which seems, astonishingly, to be some kind of comic book.

'My name is Elizabeth Costello,' she says, and sits down beside him. 'This is not easy for me, so let me come to the point. My lecture today contains references to one of your books, the von Stauffenberg book. In fact, the lecture is largely about that book, and about you as its author. When I prepared the lecture I was not expecting you to be in Amsterdam. The organizers did not inform me. But of course, why should they have? They had no idea of what I intended to say'

She pauses. West is gazing into the distance, giving her no help.

'I could, I suppose,' she continues, and now she really does not know what is coming next,'request your pardon in advance, request you not to take my remarks personally. But then you might enquire, quite justifiably, why I insist on making remarks that require a prior apology, why I do not simply cut them out of the lecture.

'I did in fact consider cutting them out. I sat up most of last night, after I heard you were going to be here, trying to find a way of making my remarks less pointed, less offensive. I even thought of absenting myself entirely – pretending I was ill. But that would not have been fair to the organizers, don't you think?'

It is an opening, a chance for him to speak. He clears his throat, but then says nothing, continuing to gaze ahead, presenting her with his rather handsome profile.

'What I say,' she says, glancing at her watch (ten minutes left, the theatre is beginning to fill, she must plunge ahead, no time for niceties),'what I contend, is that we must be wary of horrors such as you describe in your book. We as writers. Not merely for the sake of our readers but out of concern for ourselves. We can put ourselves in peril by what we write, or so I believe. For if what we write has the power to make us better people then surely it has the power to make us worse. I don't know whether you agree.'

Again an opening. Again, tenaciously, the man holds his silence. What is passing through his mind? Is he wondering what he is doing at this get-together in Holland, land of windmills and tulips, being harangued by some mad old witch, with the prospect of having to sit through the same harangue a second time? A writer's life, she ought to remind him, is not an easy one.

A group of young people, students probably, settle into the seats immediately in front of them. Why does West not respond? She is getting irritated; she has an urge to raise her voice, wag a bony finger in his face.

'I was deeply impressed by your book. That is to say, it made an impress on me the way a branding iron does. Certain pages burned with the fires of hell. You must know what I am talking about. The scene of the hangings in specific. I doubt I would be able to write such pages myself. That is to say, I might be able to write them, but I would not, I would not let myself, not any more, not as I am now. I do not think one can come away unscathed, as a writer, from conjuring up such scenes. I think writing like that can harm one. That is what I intend to say in my lecture.' She holds forth the green folder with her text, taps it. 'So I am not asking your pardon, not even asking your indulgence, just doing the decent thing and apprising you, warning you, of what is about to take place. Because' (and suddenly she feels stronger, surer of herself, more ready to express her irritation, her anger even, at this man who does not bother to speak back) 'because you are after all not a child, you must have known the risk you were taking, must have realized there could be consequences, unpredictable consequences, and now, lo and behold' – she stands up, clasps the folder to her bosom as if to shield herself from the flames that flicker around him – 'the consequences have arrived. That is all. Thank you for hearing me out, Mr West.'

Badings, at the front of the hall, is waving discreetly. It is time.

The first part of the lecture is routine, covering familiar ground: authorship and authority, claims made by poets over the ages to speak a higher truth, a truth whose authority lies in revelation, and their further claim, in Romantic times, which happen to have been times of unparalleled geographical exploration, of a right to venture into forbidden or tabooed places.

'What I will be asking today,' she continues, 'is whether the artist is quite the hero-explorer he pretends to be, whether we are always right to applaud when he emerges from the cave with reeking sword in one hand and the head of the monster in the other. To illustrate my case I will be referring to a product of the imagination that appeared a few years ago, an important and in many ways courageous book about the nearest approximation that we, in our disillusioned age, have produced to the monster of myth, namely Adolf Hitler. I am referring to Paul West's novel The Very Rich Hours of Count von Stauffenberg and in specific to the graphic chapter in which Mr West recounts the execution of the July 1944 plotters (excepting von Stauffenberg, he having already been shot by an overzealous military officer, to the chagrin of Hitler, who wanted his foe to die a lingering death).

'If this were an ordinary lecture I would at this point read out to you a paragraph or two, to give you the feel of this extraordinary book. (It is not a secret, by the way, that its author is among us. Let me beg Mr West's pardon for presuming to lecture him to his face: at the time I wrote my talk I had no idea he would be here.) I ought to read to you from these terrible pages, but I will not, because I do not believe it will be good for you or for me to hear them. I even assert (and here I come to the point) that I do not believe it was good for Mr West, if he will forgive my saying so, to write those pages.

'That is my thesis today: that certain things are not good to read or to write. To put the point in another way: I take seriously the claim that the artist risks a great deal by venturing into forbidden places: risks, specifically, himself; risks, perhaps, all. I take this claim seriously because I take seriously the forbiddenness of forbidden places. The cellar in which the July 1944 plotters were hanged is one such forbidden place. I do not believe we should go into that cellar, any of us. I do not believe Mr West should go there; and, if he chooses to go nevertheless, I believe we should not follow. On the contrary, I believe that bars should be erected over the cellar mouth, with a bronze memorial plaque saying Here died… followed by a list of the dead and their dates, and that should be that.