How do you act like someone who wants to be murdered?

It's a question that Elizabeth Taylor never solved, her role as Lise in the film of Muriel Spark's novel The Driver's Seat being singularly unsuccessful. As Spark famously later said, when asked what she thought of Taylor's performance, "She didn't look as if she wanted to be murdered, she looked as if she wanted a Martini."

As would any normal young woman. But as Morven Christie's poised portrayal of Lise in the National Theatre of Scotland's new production demonstrated, Spark's character is so far from normal, most of us have trouble understanding what's she's thinking. Perhaps we're not meant to.

The Driver's Seat was Spark's favourite novel, and the one that many of her readers least like. It's not meant to be enjoyable in the conventional sense, of course, dealing as it does with misogyny, violence, religious bunkum and death. Yet Spark brings a dark undercurrent of humour to this slim, devastating story that heightens its pitch-black theme, while also making it more palatable.

In his peerless adaptation, Laurie Samson, artistic director of the NTS, captures that mordancy at every turn. Without it, the play would be unbearable, because almost from the very start we are told that the body of this deeply troubled individual will be found the next day, stabbed to death, with her hands and legs tied, just as she had wished. From the moment she boards a plane for a holiday, and lands in an unnamed location in Italy, Lise is laying a trail of clues to her last hours, from her savagely bright clothes, to her quixotic behaviour in cafes and shops.

The idea for The Driver's Seat came from a story Spark read in an Italian newspaper. The result, however, is not an exploration of anything as ordinary as the merely peculiar, but a piece of art so sharp-edged and brittle, it seems as if it might shatter in our faces. The NTS's fragmented set evokes that sense of motility, while its self-conscious staginess also catches the modernist artificiality of the novel, in which Lise adopts various poses, deliberately to confuse. She also speaks constantly, almost Delphically, of finding "her type", as if everyone falls into a pigeonhole and is keeping up a perpetual act to maintain their image.

Rarely do stage adaptations of novels meet expectations or match the original for effect. I'm not an avid theatre-goer because, at a formative age, I discovered that for every good play there were nine dreadful ones to endure. Maybe that ratio has changed, but if so it's too late to cure a preference for the theatre of the page. But with the NTS production, my prejudice was given no chance to take hold. From the opening minute, where we see Lise at her office desk, going quietly crazy, one's sleeve was caught in the emotional wringer, and for the next 95 minutes the Lyceum audience was dragged through the mangle, by turns laughing and horrified as Lise's quest for her killer unfolds.

One of the many remarkable things about this play, which was impeccably performed by a quicksilver cast, is how faithful it is to the book. Often when that's the case the result is stultifying or worthy. Not so here. While Spark's novel has a visual theatricality about it, as does all her work, it must have been fiendishly hard to adapt, cutting as it does between scenes and time frames.

Yet Sansom renders it seamlessly, barely stepping beyond the bounds or dialogue of the book - and where he does, to good comic effect. Morven Christie brings just the right balance of the nearly insane and the anguished to her part, and the widow who acts as her foil is played with superb bewilderment by Sheila Reid, thereby anchoring the spiralling nastiness of the plot. By its end, of course, you are left with the sinking realisation that the horror of the story is but an echo of the brutality and irrationality of real life.