What a disappointment the Chocolate Factory is these days! What an example of mislaid daring!

In 2005 it won the Evening Standard Best Newcomer Award for its adventurous line in new drama.

Nowadays it is best known for imaginative re-inventions of old musicals bound for the West End and uninspiring revivals, of which Christopher Hampton's dramatisation of the love/hate affair between the romantic poets, teenage Arthur Rimbaud and married, plain Paul Verlaine is the latest and inadequately acted example.

Total Eclipse premiered in 1968, just after the abolition of stage censorship that had precluded depiction of gay relationships.

This brilliant writer's reaction to the new freedom was to write as if impelled to use tongs to handle the delicate subject, thereby, perhaps, sparing himself direct contact with a gay passion he wished to consider but dared not explore: the lovers scarcely touch each other throughout.

Paul Miller's cumbersome, emotionally monotonous production, with its narrow traverse-stage, proves ill-suited for scenes requiring communication between the lovers, whose faces were often masked from my view.

Tracing the poets' shaky dalliance through four years of quarrelsome wandering through France, London and Brussels, Hampton throws little light on what drove Verlaine to ruin his sexually vivacious marriage and run away with the teenager.

Was it a burst of uncontrollable gay eros? Was the younger man in love or opportunistic? Hampton offers few clues but plenty of sardonic, witty paradox voiced by Rimbaud. "I assure you I get no more pleasure from pain than I do from pleasure," he says.

A psychological/religious gloss is placed on the relationship. Verlaine is indentified as a crapulous narcissist, prone to violence and masochistic submission to Rimbaud's cruel tongue and will.

Forced to choose between body and soul, both men end up possessed by Catholicism. In a final, sentimental reverie Verlaine fantasises that his hands, which Rimbaud stabbed in crucifying vehemence, are kissed by his lover in redemptive consolation.

Daniel Evans's undercharged, armour-plated Verlaine cannot make this final reverie touching. He should be "transfixed" at the first sight of Jamie Doyle's suitably cool, sexy and uncannily mature Rimbaud, but remains quite blank.

He captures none of the poet's conflicted sexual passions and uncertainties, while Doyle, frozen in a pose of inscrutable cockiness, never lets us glimpse the concealed vulnerabilities and engimatic desires that control Rimbaud.

• Until 20 May (020 7907 7060).