Single, gay New York banker Willem - more distant than estranged from the rest of his family - returns to his parents' home in Holland for his brother's funeral. And yet despite the thousands of miles travelled, the distance between Willem and his family remains.

This is one of two poignant observations that emerge from the 75 uninterupted minutes of Simon Stephens's new play, almost unnoticed, like a change in the weather. The other is that Willem is probably now closer to his brother in death than he ever was in life. Willem has written a series of confessional and confiding letters to his late sibling and it is this unsent correspondence that forms the structure of the play - a terrifically performed, 75-minute one-man monologue played by the wiry Dutch actor Eelco Smits.

The production itself - directed by Dutch theatre company Toneelgroep's Ivo van Hove, whose previous Young Vic show was the all-conquering A View From a Bridge - exudes class. The action takes place in Willem's monastically under-furnished New York apartment (designed by Jan Versweyveld) with two windows looking out onto an abyss of black. Occasionally snow falls prettily. And in one beautifully staged moment the passage of time is evoked by the shadow of Willem's now naked body travelling across the bare walls.

But what prevents this piece - a collaboration between Stephens (probably best known as the adaptor of The Curious Incident of the Dog in the Night-Time) and American indy singer-songwriter Mark Eitzel - from being as compelling as all these elements promise, is the nagging doubt that Willem may not deserve all the talent that has been devoted to telling his story.

Eitzel's song is beautifully worked into the narrative as half-heard, semi-remembered moments before the song's simple beauty is fully revealed.

But in the longish passages that relate (still to his brother) the solitude of Willem's life and the sense of loss over a past lover, Isaac, they also revealWillem's somewhat shallow susceptibility to his ex's whimsical musings. For instance, Willem describes how, during a conversation about the Dutch founders of New York, Isaac wonders if they knew that they were living in a Golden Age. "Or do you only ever realise you're living through a Golden Age after it has gone?" he adds, making Willem fall in love with him all over again. I mean, it's not that good.

But monologues can be terribly exposing that way. The speaker needs to be awfully interesting to justify his or her stage time. And ultimately, Willem is not that person.