Appropriate Adult
ITV1

If it is hard to watch Appropriate Adult (4 and 11 September, 9pm), it is also, thanks to Dominic West's astonishing turn as Fred West, hard to turn away. What a star he is.

In a recent interview, the estimable Neil McKay, who wrote the series, singled out for praise Emily Watson, who plays Janet Leach, the social worker who was semi-illiterate West's designated "appropriate adult" during police interviews. Yet, for me, Watson's painfully mannered performance - called upon to convey almost any emotion, she invariably does that crazed, Nookie Bear thing with her eyes - only adds to my strong distaste for Leach, a woman who not only seems to have become creepily transfixed by West but then also sold her story to the Daily Mirror, something that definitely was not encouraged on the appropriate adult training course. (McKay believes that she deserves our sympathy.)

West, on the other hand, is so natural as to be physically alarming. I felt sick at the sight of him and sick at the sound of his voice. The nausea stayed with me long after the credits rolled. It is a superlative impersonation and should win him a Bafta, if the judges don't wimp out.

Everything is on his side - and I mean everything. McKay, who specialises in these tricky areas (he also wrote See No Evil, a drama about the Moors murders), is an assiduous researcher and his efforts are reflected not only in his superb script, which seems never to strike a bum note, but in the sets, too. At 25 Cromwell Street, there was a bar complete with a full set of optics, a "mural" featuring palm trees and a bright blue sea and a clattering, beaded curtain. On a wall was hung the framed maxim: "A mother's heart is like a rose - always open, always loving." In the basement, a room whose secrets I can hardly bear to contemplate, there was wallpaper decorated with the silhouettes of dancing girls. In context, these things alone are enough to give one bad dreams.

Just right, too, is the supporting cast. Monica Dolan is perfect as foul-mouthed Rose, her frumpy clothes so unnervingly at odds with
her obsession with "dirty" sex. In repose, upholstered in a dusty pink bathrobe, she looks almost cosy. Then, she opens her mouth and out it comes: compacted filth, spitting anger, a thin-skinned plaintiveness that we know dissipated only when she was enjoying her vile hobbies (not for nothing did Gordon Burn call his book about the Wests Happy Like Murderers).

Also wonderful is Sylvestra Le Touzel as DC Hazel Savage, a copper in Deirdre Barlow spectacles who takes everything - even Fred and Rose - in her stride. In the field where West had buried his first wife, Rena, he stared about, wistfully. "Takes me back, you know," he said. "We've come to find your first wife's remains, Fred," Savage replied, in the purest, dankest Gloucestershire accent (it made me think of moss and Findus Crispy Pancakes). "We're not sightseeing."

Still, the main prize must go to McKay and his script. I don't believe that this drama needed to be made and I'm certain that I have not learned anything from it, beyond a few sickening details. Several moments left me longing to rush outside for fresh air: when West joked to the police that he got on with a killing while Rose was on a "long ol' walk to Tesco"; when he called Leach a "good girl" for helpfully suggesting that he use the abbreviation "approx" in conjunction with the number of murders he'd committed; when he described butchering his daughter's body so that it would fit neatly inside a dustbin (his hands merrily formed the shape of a cylinder). I would not call this a desecration, however. If anything, it is a kind of memorial, a reminder that what the tabloids like to call evil lurks in rooms where people watch Neighbours, sleep in fancy four-poster beds and load their sofas with pink cushions emblazoned with the legend "Mum".

One wants to use the word "monsters", but it doesn't even come close, does it? Something went terribly wrong with the Wests - with both their minds and their souls. You could have got talking to them in a supermarket queue and thought them peculiar, or not, and then you would have gone home and forgotten all about them.