In the October of 1893, Debussy started to plan an opera on the contemporaneous 'prose drama' Pelléas et Mélisande by Maurice Maeterlinck. Debussy completed the score two years later but the opera was not heard until 30 April 1902 - a delay partly caused by Debussy's perfection-seeking revisions and negotiations with the Opéra-Comique in Paris.

In his search for a new kind of French opera, Debussy looked to Wagner in his wish to write continuous music and in the use of leitmotifs, but the colours, expression and harmonies of Debussy's writing is recognisably 'French'.

Debussy's operatic setting of Pelléas et Mélisande (a story that also attracted Fauré, Schoenberg and Sibelius) is regarded as something of a challenge - for performers, producers and listeners. Over five acts and 150 minutes or so of music, Debussy's ability to sustain a mostly slow pace is astonishing - through multifarious dynamic contrasts, subtle changes of colour and shifting harmonies that constantly divert the ear and paint pictures. Furthermore we find out all we need to know about the characters and their circumstances through the orchestra. When emotions become heated or violent, or when the oppressive atmosphere is gladdened by a chink of light or a breeze, this is meticulously sounded in the orchestra through brighter textures, quicker tempos or the use of fortissimo.

The orchestra and the conductor are crucial to the success of Debussy's version of Pelléas et Mélisande. In the current production hosted by The Royal Opera (a co-production with the Salzburg Easter Festival) Sir Simon Rattle is a deeply sympathetic and perceptive interpreter of Debussy's discriminating yet revealing music. At this first night the inaugural sound to be heard, when the lights had lowered and Rattle was about to conduct, was the ringing of a mobile phone. Fortunately this stopped before the first music was heard. A beautiful, veiled sound emanated from the pit. We see the lone figure of Mélisande. She becomes very nervous of Golaud, who is also lost in the woods, as he enquires of her. Bit by bit they become closer. They marry and return to Golaud's family castle, a lonely and inhospitable place occupied by Geneviève (mother to Golaud and Pelléas), Arkel (the king), Yniold (Golaud's son) - and, of course, Pelléas himself. He is Golaud's half-brother, someone that Mélisande is unsure of, but their relationship grows, partly through innocence and naivety. Golaud has his bloody revenge at the end of Act IV when he stabs Pelléas to death - the violence all the more shocking for the restraint shown elsewhere.

Debussy's opera is a study of the human condition, of relationships and feelings. A difficult work to stage, though, given there is little action beyond the revealing of the characters, their surroundings and their emotions. Under the direction of Stanislas Nordey, the production team has not tried to inflate anything nefarious to add 'entertainment'. Lighting is deliberately gloomy, save when extra brightness matches the text, and the stage is dominated by moveable gigantic tombstone-like designs that open up like trophy cabinets to display various collections of pertinent artifacts. In Act IV the stage is lit blood-red, a portent for the murder of Pelléas with which the act climaxes. An insular, hermetic world is well suggested. It is difficult to know what could be added. Similar effects could be achieved by other means and one can imagine different costumes for the castle inhabitants other than satin-white and bejeweled uniforms that seem more suitable for space travel than an earthly kingdom.