`Melon': lightweight people in a trivial world. Simon Gray's latest play bows in London

Simon Gray's newest and much anticipated play, ``Melon,'' at the prestigious Theatre Royal Haymarket, does not measure up to his previous successes, such as ``Butley,'' ``Quartermaine's Terms,'' and, in America, ``The Common Pursuit.'' ``Melon'' opens with Mark Melon (Alan Bates), an acid-tongued, ruthless and successful publisher, explaining to the audience that he has recently had a nervous breakdown. The reason: The Melons' ``open marriage'' has backfired. Both Mark and his attractive, clever wife have been engaging in extramarital affairs, which they have accepted with credible sangfroid. Indeed, Melon seems to relish his wife's behavior, until he learns that her lover is one of their closest friends. What was a kind of game is transformed into a deadly serious business. And as Melon's hold on personal relationships becomes unglued, so does the rest of his world.

The story is told via flashbacks, from Melon's manic viewpoint, complicated by shock treatment he has received as a patient in a hospital psychiatric ward. Hence there are some surreal moments, as when his wife and circle of friends, whom he once dominated completely with his acerbic quips and sardonic super-cool manner, sing to him in unison, symbolic of their ``happy harmony,'' or alternatively whisper ``cuckold'' at him in haunting fashion. He often qualifies what the audience sees by saying that these are the essences of what took place, rather than accurate renderings.

Ultimately, ``Melon,'' as a piece of theater, gives the impression of saying something quite different from what the author evidently intended. Melon is not convincing as a truly talented man who has squandered his gifts, and ultimately his mental balance, through conforming to ``conventional'' middle-class life. Melon's crackling glibness suggests not an underlying brilliance but mediocrity itself - and, deep down, he knows it. Melon, by the end, hasn't invoked our sympathy, or even much of our interest, because there isn't much to him.

Moreover, in focusing almost exclusively on the sexual element of the Melon marriage (which is, apart from anything else, rather hackneyed), Gray misses entirely the crux of the problem of the characters he has created.

The Melons are lightweight people, who live in a trivial world in which material and social success serve to continually reinforce superficial values: The sexual, largely unfulfilling, affairs are merely one of many outer manifestations of a far more basic malaise.

In the role of Melon, the undeniably talented Alan Bates makes use of certain stylized mannerisms - staccato delivery, droll expression, stillness punctuated by small quirky movements of the hands. While these make for an engaging performance, they do not seem to be carefully thought-out aspects of the character he plays.

Even more disappointing is Christopher Morahan's direction. An accomplished director of stage and television (most notably of Britain's internationally acclaimed TV epic ``The Jewel in the Crown''), he nevertheless injects ``Melon'' with some oddly clumsy moments, such as using large, thudding screens to block off the stage when the action switches from Melon's home to his office. Later, the method is abandoned and one is left wondering why the screens were ever used in the first place.