One Under, Tricycle Theatre, London

Winsome Pinnock's new play, One Under, is an instructive case.

Winsome Pinnock's new play, One Under, is an instructive case. There is something so compelling and so sincerely pondered in the material that the resulting event manages to survive pretty abominable direction (which, at points, leaves very good actors floundering as if they were in a rogue variant of Acorn Antiques), and the manifest lack of anything approaching decent script-editing on this project. Was there no one around who could have said, "Enough, already," as needless scenes and elaborations watered down the strong essence of the thing?

The play shifts between the prelude to and the aftermath of the suicide of a 30-year-old black man, Sonny (Daon Broni), who has thrown himself under a Tube train (hence the title). The primary twist is that, for reasons that finally become all too clear in a last-minute, over-explicating flashback, Cyrus (Brian Bovell), the driver of the train, gets it into his head that the young man he has accidentally killed is his biological son, taken for adoption as a child. That in itself is an intriguing basis for a play. Imagine: a loved one dies, and on your doorstep appears a guilty, insistent stranger whose deepest reasons for remorse are obscured from you. Whose bereavement is this anyway? Et cetera.

Pinnock, to some extent, writes that play (though, unfortunately, it is precisely that strand that is subject to the most pernicious directorial neglect). The trouble is that, concurrently, she writes a number of other plays, too. I sat there aghast at the squander. Could no one tell her that this wasn't a single, but an oeuvre packed into an unwieldy two and three-quarter hours?

For example, the suicidal man seeks out Christine (Adie Allen), a woman in her late thirties. She is known, from the newspapers, to be still in psychological pursuit of the motorist who killed her child in a hit-and-run accident. Christine works in a dry-cleaners - and wasted in this work is the play that is to be written about the odd tragicomic possibilities that arise when you take custody of the public's clothes for a while. The potential for borrowing; the potential for finding revealing things in the pockets - such considerations are handled deftly but too glancingly here. Instead, there's an obvious and plodding sequence of scenes in a hotel where the death-bent man wines, dines and has what might be misinterpreted as "last request" intercourse with the unwitting Christine.

Yet another play deals with the weird relationship between her and the man who thinks that he is Sonny's father. As with Wild East, the April De Angelis play now on at the Royal Court, you feel that there should be people employed in theatres whose express purpose is to prevent writers from outsmarting themselves and being clever and structurally sophisticated at the expense of their own keenest insights. You don't have to cram a career into a single work. That said, there's some evocative scene-setting here - the book-end episodes in which Cyrus finds himself on a train that has come all the way to his starting point struck a strong chord with this reviewer who, in his selfless dedication to this newspaper, spends most of his life on trains.

To 5 March (020-7328 1000)