Penthisilea, New End Theatre, London

An evening of strange delights

The characters are implausible, the dialogue preposterous. It begins like this. Two middle-aged men are sitting side by side, staring into space.

"I get this pain," one says, "in my legs. It's bloody agony. Even the weight of the sheet is too much to bear."

"That's su... " (it rhymes with "zoo"), his friend attempts to interrupt.

"Even the sheet has me screaming in... "

"That'll be su... "

"Bloody agony. Eventually," he adds, "your legs drop off."

"That", the second character says, "is sumo gout."

"What?" says the first. "Like the Japanese wrestlers?"

"No," says his friend. "It begins with 'ph'."

This remarkable exchange, which I reproduce word for word, occurred between two regulars on bar stools at the Duke of Hamilton pub, next door to the New End Theatre, just before curtain up. As a result, once Penthisilea began, I had the feeling – unusual when contemplating Greek tragedy – of having entered a world of greater normality.

I'd sensed immediately that it would be a captivating production. It was a classic illustration of Whiteside's law of London theatre, which I formulated several years ago in the final stages of a day that began with a press launch for a new brand of mescal and ended, by a process that has still not been explained entirely to my satisfaction, with my losing consciousness in the rear stalls while watching Starlight Express. Whiteside's law, stated simply, says that my level of interest in any metropolitan drama is inversely proportional to the size of the audience it attracts.

The New End seats 80. Four empty seats on the back row were sternly marked: "Reserved". There were 10 of us in the audience, so when one old trout slipped out for a pee during Act II, the cast actually outnumbered us by one – two, if you count the dog.

Tom Kempinski, who is best known for Duet for One, his moving piece about a violinist with multiple sclerosis, has been a fiercely original voice in British theatre since the Sixties. Penthisilea is the second of four plays in a new Kempinski season at the New End Theatre called 'Love and War'. This is a strikingly original adaptation of the story of the Amazon queen Penthesilea, who – in this version at least – divides her affections between the Greek hero Achilles (whom she murders) and a black spaniel called Vexoris (Alice, in her first dramatic role).

This productionmanages to combines black humour – Richard Laing's Achilles has a maniacal swagger of the kind Rik Mayall might bring to the role of Goebbels – with some disturbing observations about the psychology of men who slaughter. In the latter respect, recent events have given Penthisilea a terrible new resonance. The finest moment comes when Astyanax, splendidly played by the 10-year-old Harry Jardine, speaks Kempinski's elegant, understated lines over the tomb of his father, Hector. "I cried a lot today, daddy," he says. "Not as much as yesterday. More than the day before."

In the end, it didn't seem to matter that the audience could have gone home in two cabs. In the course of the evening, we laughed, and at least one of us wept. Between them, Penthisilea and the Duke of Hamilton – where I'm informed the sumo gout men can be found every night – made this my most memorable night out this year.