By his own admission, Christopher Wheeldon is not a choreographer with a world-changing mission. His gift is for craft rather than iconoclasm. But in Tryst, his new work for the Royal, he has not only advanced into fascinating new territory, he has given the company their first major work of the 21st century.
Wheeldon's score Tryst, by Scottish composer James MacMillan, is certainly leftfield in ballet terms - it does not cry, "Dance to me." But the music's energy is everywhere in the ballet. Texturally Wheeldon uses its shimmering strings to orchestrate his own spacious masses of movement, with swooning, fidgeting details that beautifully disorient the choreography's surface. Cutting across the strings are peremptory blasts of brass that galvanise jagged hieroglyphic angles in the dancers' moves. This is a ballet that seems to come direct from the Celtic fringes - silvery, mystical and cold.
Structurally the orchestra's shifts between dense washes of sound and spare instrumental lines are mirrored in the choreography's rapid fluctuations of scale between 20 dancers and two. But even more interesting are the odd phrases that Wheeldon finds to negotiate the music's trickiest points of transition. Limbs and hands braid into knots, they swing direction, like compass needles, and their very quirkiness allows them to unlock the music's structure with brilliant clarity.
Most daring is the central duet for Darcey Bussell and Jonathan Cope. It starts with a bar of pale light glimmering across the stage like a northern dawn. (Natasha Katz's lighting is wonderful, changing through the piece like weather.) MacMillan brings into play a series of folk melodies - dark, plangent but never fully stated - and Wheeldon responds with a coiling pas de deux in which the dancers are in a state of dreamy flux. Slippery, secret and intent, they remind us of seaweed drifting in a dark sea, of ferns growing round a rock, of a man and a woman in a trance of emotion. What is ravishing about this piece is that while it rarely flags up its own startling invention, while it generously celebrates the dancers' classicism, it looks like nothing we have ever seen before.
Sharing the programme with Tryst is Tudor's The Leaves Are Fading and Ashton's A Month in the Country, based on Turgenev's play. In the latter's draped and decorous world, lovers in drawing rooms do not rip off their clothes. But Sylvie Guillem and Jonathan Cope (Natalia Petrovna and Beliaev) strip Ashton's choreography and Chopin's music to a drama so fabulously naked that it is barely decent to watch.
· In rep until Saturday. Box office: 020-7304 4000.
