Heart of Darkness, Royal Opera House, London

Published in 1903, Joseph Conrad's Heart of Darkness still reverberates. Its narrator Marlow, like Conrad himself, worked on a steamboat for Belgian ivory-traders in the Congo, and has a triple quest: to penetrate the jungle, to find Kurtz – the Faustian personification of predatory Europe – and to find colonialism's dark heart. Orson Welles made a radio play from it; T S Eliot harnessed Kurtz's dying cry "The horror! The horror!"; it became the mainspring for Francis Ford Coppola's Apocalypse Now.

Conrad's prose is verbose and allusive, and though some passages feel like arias, it's not an obvious candidate for operatic treatment. Yet Tarik O'Regan and his librettist Tom Phillips have done just that. And when the lights go up on the cat's cradle of ropes that constitute Robert Innes Hopkins's evocatively nautical set, one is ready, with the gnarled Jack Tars surrounding tenor Alan Oke's Marlow, to listen to Marlow's tale.

Unfortunately, he comes across as one of those obsessives one instinctively avoids, delivering convoluted and gnomic thoughts in melodic lines reminiscent of Britten writing for Peter Pears at moments of high drama. And as the tars transmute into uncharacterised deckhands in the Congo the lack of dramatic pulse becomes a problem.

The figure at the centre of Conrad's story is a moral enigma: the literary strategy is to induce readers to invest that figure with their own conceptions. O'Regan and his director Edward Dick have made Kurtz a flesh-and-blood creature, and only at this point, thanks to a commanding performance by the Danish bass Morten Lassenius Kramp, does some real drama take off. Kramp sings his melismatic death-aria with awesome authority, after which the rest of the cast sings a haunting chorale. Gwen-Ann Jeffers, doubling as River Woman and as Kurtz's fiancée, adds her own vocal authority.

O'Regan may not have found a unifying vocal style, but the sound-worlds he conjures up with the Chroma Orchestra's percussion, woodwind, strings, harp, and celeste are very beguiling. Since this opera is still a work in progress, he and Phillips should now find a way to acknowledge the African grief at this great novella's heart.

To 5 November (020 7304 4000)