`Someone must have been telling lies about Josef K, because he was arrested one morning without having done anything wrong."

From the plangent opening words of Franz Kafka's novel The Trial, K is propelled into a world in which nothing is what it seems. He is arrested but not charged, and is free to carry on his job as a senior bank official. His efforts to progress his case only compound the confusion and, as his advisers - an uncle, advocate and others - tell him, worsen his position.

But how can a man be guilty, cries K. It is an appeal wasted on those who appear to believe the opposite, from legal authorities to commoners to clergy. And, finally, when K comes face to face with his executioners, he lacks the will to defend himself, even to ask for help which may be available. He dies, in his own words, like a dog, never having reached the court or seen the judge who condemned him.

The Black Box International Theatre of Prague are at the Crypt, for this week only, with a faithful and telling staging of this overpowering parable. One actor - Scott Bellefeuille - plays K; four others, with the help of atmospheric masks and costumes, play all the others, over 20 of them. In about 90 minutes, scene follows staccato scene as K treads his via dolorosa. It is a hypnotic realisation of the book.

Gwen Orel adapted the work for the stage and, apart from a few intrusive Americanisms - too specific as to time and place - has done an exceptional and sensitive job. Nancy Bishop's direction has pace and control; nothing is wasted. And the acting, notably by Mr Bellefeuille with his lead opportunities, and also by Jan Unger, Rich Gold, David Maj and Petra Lustigova, carries total conviction.

Runs until Saturday (booking at 01 6713387)