Koos Sas, Tricycle Theatre, London

( LAUREN CLIFFORD HOLMES)

The second presentation in the Tricycle's South African season is a rather simple-minded Bonnie and Clyde or Ned Kelly parable, with a cheerful outlaw, Koos Sas, chased across the veld by a policeman who wants his bum for booty and a hired Scottish phrenologist who wants his skull for racist researchers in Vienna.

I'm afraid even that prosaic summary makes it all sound much more exciting than it is. And there's more: the outlaw's girlfriend is raped by a white shopkeeper who in turn is murdered by her brother; and Koos unwittingly takes that rap when finally cornered by the authorities on a remote farmstead.

The real-life Koos was imprisoned for the murder in 1917, but managed to escape and spend five years on the run, stealing sheep to justify his own legend of being a notable mutton-guzzler. He was also handicapped with small feet, though he could outrun any horse. These gobbets were discovered by writer and director David Kramer in a small museum where Koos' skull was on display as that of a man of "bushman extraction."

So Kramer's musical, performed in Afrikaans with surtitles, mixes the romance of the chase, and Koos' long-distance love affair, with an angry exposition of the anthropological skull-gatherers whose research was designed to prove that the indigenous Khoisan people were of an inferior caste to that of the colonial trekboers.

The trouble is that Kramer's music and lyrics are incorrigibly jaunty and one-paced throughout, so that a song about the dream of water or a girl's beauty sounds exactly the same as one about the sinister Scotsman with a camera in search of bushmen's graves.

Musically, the show is scuppered by having the actors sing live (and over-microphoned) against a backing track of non-electronic sound, which makes the enterprise look slightly ridiculous. This also deprives the event of the live urgency needed to stiffen up the charm quotient; and there's lots of untethered charm in the performances of Loukmaan Adams as the Koos on the loose and Natalie Cervati as the girl in a whirl.

Kramer had a big success here ten years ago with his Kat and the Kings 1950s nostalgia burst, but this probably more authentic and certainly more austere musical fable hasn't made the journey quite so well.

To 1 August (020 7328 1000; www.tricycle.co.uk)