La Bête, Comedy Theatre, London

"La bête" is a beast and a fool in French, and it's one of the puzzles in Matthew Warchus's colourfully inflated, Broadway-bound revival of this 1991, 17th-century oddity that you never really know to whom the title refers: the actor, the writer or the patron. These are the three protagonists in a stylish, one-off rhyming text by American playwright David Hirson, and they are played by Mark Rylance, David Hyde Pierce and Joanna Lumley.

For about one hour, the show is enjoyable because it's so intriguing. A magnificently lit banquet is in progress on the Languedoc estate of the princess. The stage then literally deliquesces in Mark Thompson's design into a grand library where battle is joined between the favoured playwright, Elomire (ie Molière) and the upstart vaudevillian Valère, played with Ken Dodd comedy teeth by Rylance, spitting on every line and chomping on his own integrity.

But what is Hirson actually proposing? An argument about the theatre, the conflict between intellectual and commercial, and an age-old bust-up between old and new orders in show business?

It should be more than enough, but the play runs badly out of steam in the last 45 minutes, which seem to go on forever. But Rylance makes a virtuoso triumph of his uninterrupted 40-minute monologue, despite the lack of stage vivacity around him.

Ms Lumley is gorgeous and beautifully coiffed and dressed, but you don't know, really, where she's coming from. Hyde Pierce's banked-down acting is a subtle delight, and Rylance proves yet again his astonishing, protean versatility. But his Valère is a feeble follow-up to his shape-shifting Johnny Rooster in Jerusalem in a play that promises much more than it delivers and ends up curling into a cul-de-sac of self-referential platitudes.

To 4 September (0844 871 7622).