If you're looking for a cosy evening at a musical then Stephen Sondheim's musical thriller Sweeney Todd is not for you.

This chamber version of his Seventies show, here produced by the Theatre Royal itself, is claustrophobic, dark, unsettling and a gore-fest of spilled blood and sliced throats.

Under John Doyle's vivid direction the show is a triumph and marks the appearance of a Jason Donovan you will hardly recognise.

A little weak in the title role, he first appears as the blood-thirsty barber intent on revenge for the loss of his family when he emerges from a coffin, clad in a black leather jacket and grizzled stubble.

This is a modern-dress production. Donovan has come a long way from Ramsay Street and is no longer the fresh-faced youth of Joseph and Chitty Chitty Bang Bang fame, appearing as a moodier, mature man. He wields his cut-throat razor with relish, sending his victims' bodies downstairs to Mrs Lovett's meat grinder and bakehouse to become succulent meat pies.

Donovan acquits himself well, although he could do with a darker voice. But his fans were obviously well pleased with his performance.

A highly-talented ensemble cast of ten present this show in Brechtian style, all on stage virtually the whole time. In addition to acting and singing they play a range of musical instruments including piano, violin, flute, clarinet, double-bass, cello and accordion.

The show captures Sondheim's musical style which is hard-edged and in the love songs quite lyrical, combining the influences of Kurt Weill and Leonard Bernstein and with lyrics which are cutting and very witty.

Stepping into this show is like stepping in to a Berlin cabaret of the Twenties where you will be both shocked, amused and confounded by the horror of Todd and Lovett's crimes and the tender love story that runs alongside. If I were handing out awards, Harriet Thorpe would get several gold stars for her performance as the bawdy, big-hearted Mrs Lovett.

Running until Saturday, February 4