Let's Start with a bit of poetry: "Howe'er it be, it seems to me,/ 'Tis only noble to be good. / Kind hearts are more than coronets,/ And simple faith than Norman blood." (Tennyson, "Lady Clara Vere de Vere".)

This is where Robert Hamer got the title of his 1949 film, Kind Hearts and Coronets from. He took the plot, however, from a little-known novel by Roy Horniman, Israel Rank; and Giles Croft has conflated the two for his Kind Hearts and Coronets, which has just opened at the Watford Palace.

Quite why Croft should want to adapt such a well-known, well-loved film for the stage is something of a mystery, at least before curtain up. The play begins with a television screen showing the film's opening scene, in which the public hangman prepares to do his duty by the 10th Duke of Chalfont - Louis Mazzini, who has murdered his way to the title from suburban obscurity. Then Mazzini himself (played by Simon Coury) rises from his chair to announce that, while you probably know his story already: "I can get closer to the truth." It sounds a rather silly claim - a post- modern conceit - but Croft's version lives up to it surprisingly well.

The film is a blithe, if somewhat blood-stained farce - Dennis Price, the original Mazzini, is too charming, his victims (all played by Alec Guinness) too insubstantial and cartoonish for you to take his murderous career altogether seriously. The murders, too, are really just boyish pranks which happen to have lethal consequences - untying punts, shooting down balloons, mixing together chemicals to make a big bang; and Mazzini's methods mean that he's always at a distance from the crime, leaving the viewer room to sympathise. And there's a vein of light, epigrammatic wit that reminds you of The Importance of Being Earnest.

Watching Croft's version, though, you realise that the story is really closer to the narcissistic amorality of The Picture of Dorian Gray. (Having been browsing that book the other day, I can't help noticing that Sibella, Mazzini's lover, marries a man called Hallward, which was also the name of the man who painted Dorian's picture. I don't know whether that's hommage or coincidence).

Unlike the film, in the play it's not long before Mazzini has to get his hands dirty: he strangles his nice cousin Harry, sets fire to the fey Ughtred (the camp predator with a touch of Wilde), then gloatingly recounts his career in crime to the Duke while poisoning him with aconite. You see, too, that his relationships with the high-principled Edith and the more willing Sibella are an exaggerated reflection of the Victorian values which enabled a man to place a high price on some women's virtue, while paying for others' lack of same.

This new, harsher moral vision isn't something Croft has added to the film version - he just shows you that it's already there, buried under the style. Croft's adaptation is a fascinating bit of commentary; but it never quite achieves a life independent of the film. In stripping away the light, frothy surface of Hamer's version, Croft has come up with something that isn't simply darker, but heavier, slower and duller. Coury is well-cast - flippant, but with an edge of neurosis and, as Croft points out, clumsiness; but he plays the part too much on one note. Jamie Newall's multiple characterisation of the murdered D'Ascoynes is well-managed, with some impressively quick changes, but he's a little too anonymous for the feat to have much impact - especially since Robin Harvey-Edwards plays almost as many parts. The result is that it is less a good night out than an intriguing academic exercise.

More poetry, Kipling this time. "East is East, and West is West, and never the twain shall meet,/ Till Earth and sky stand presently at God's great Judgement Seat." They do meet in Ayub Khan-Din's East is East, a sparky comedy of interracial marriage in Seventies Salford, which did well enough at the Royal Court last year to get an early revival at the Theatre Royal, Stratford East.

The story concerns the Khan family, ruled with a rod of iron by George, known to his children as Genghis, who has lived in England for 35 years without ever properly leaving Pakistan. He tries to bring up his offspring to respect tradition - insisting, for instance, on having all his sons circumcised; the play opens by revealing that the youngest, Sajjid, a twitching, parka-clad obsessive, still has his "tickle-tackle" intact. But his family, with the tacit help of their English mother, Ella, have become more or less westernised. The tension between his aspirations and theirs is becoming unbearable.

The play certainly deserves its reputation - Khan-Din has an admirable gift for writing dialogue that's funny without seeming contrived, and the climactic scene, where the family meets the father of the girls George has covertly arranged for two of his sons to marry, is a superbly orchestrated piece of farce. There's some excellent acting here, too, particularly by Linda Bassett as Ella, a performance of tremendous depth and comic sympathy. The production is a little marred by some clumsy direction, though - especially some muffed scenes of violence.

Yet more poetry in Kitchensink at the Tricycle - though here poetry is only referred to now and then, as the hobby pursued by Helen, the central character. It's a rather cheap way of indicating that she has untapped spiritual depths, and typical of the way this show - by Irish company Passion Machine - operates. The action takes place over 30 years, in a succession of half-built houses - we meet Helen first as an optimistic child, then as an idealistic teenager, then a newly-wed, then a disillusioned mother, then looking forward to grandmotherhood. And finally, we meet her as a widow, wondering what happened to the woods and streams of her childhood (answer: they've all been built over). The messages and structure are banal and the dialogue cliched. Kitchensunk, as far as I'm concerned.

'Kind Hearts and Coronets': Watford Palace (01923 225671) to 22 Feb. 'East is East': Theatre Royal Stratford East, E15 (0181 534 0310), to 8 Mar. 'Kitchensink': Tricycle, NW6 (0171 328 1000) to 1 Mar.

Robert Butler is away.