Ruth Rendell’s novel A Judgement in Stone is generally reckoned to be one of her finest achievements. This is all the more remarkable because on the first page of the book, the writer tells us who died and who the killer is. As a result the book is essentially not a ‘who done it’, but a ‘why done it’.

The challenge for Simon Brett and Anthony Lampard when adapting the book for the stage was how to square this circle - how to maintain both the audience’s attention and the tension of the story. They do so by telling us who died, but holding back the information as to ‘who done it’.

The story unfolds in two time-frames. Firstly, the present in which two detectives pursue their investigation and interview suspects. Secondly, in the recent past as we see the various characters interact – starting with the day Eunice Parchman is interviewed for the job of house-keeper in the Coverdale household and ending with the day of the murders.

When the theatre curtains opened and the stage was revealed, the set reminded me immediately of the set of Agatha Christie’s Mousetrap: a panelled country house with books and stained glass windows. The play is set in the late 1970 but in many respects it could have been thirty or forty years earlier, though the significance of a cassette recorder in the plot and the white fashion boots worn by Joan Smith (played with scene-stealing élan by Deborah Grant) are a sharp reminder that it isn’t.

There are strong performances all round by the cast. Chris Ellison – most familiar to TV watchers as Frank Burnside in The Bill – and Ben Nealon play the two detectives trying to work it all out. Older audience members will recognise with pleasure Shirley Anne Field playing a disapproving Eva Baalham who is forced out of her job. Younger audience members will recognise Anthony Costa (he of the hugely successfully boy-band Blue) as the ex-con from the village. But unquestionably it is the terrific performance of Sophie Ward as Eunice Parchman which stands out. As the housekeeper with her own secrets and an inability to understand what is going on around her, it is she who holds our attention to the very end.

Directed by Roy Marsden (Inspector Dalgleish in the TV adaptations of P D James), this all adds up to a very entertaining and expertly presented evening out. Perhaps a case of Agatha Christie meets J B Priestley’s An Inspector Calls. Underpinning the story are issues of class and education and the power which these things (still) give to those who have them. But it is Rendell’s fascination with how and why ordinary people can end up doing terrible things (and often end up regretting them) which lingers long after the theatre curtains have closed.