Before the Tempest, After the Storm / Asyla, Linbury Studio Theatre, ROH London

Cathy Marston's new dances, supported by the Royal Opera House's Artists' Development Initiative, are an encouragement to go to the opera. This was the idea: her programme was made to sit alongside Thomas Adès's new opera, The Tempest, which had its premiere at Covent Garden this week. Marston's use of an earlier Adès score makes me keen to hear his opera. Her two Tempest duets doodle at the edges of the play.

Marston doesn't merely retell the story of The Tempest. Her two duets show events from the edges of Shakespeare's narrative: the birth of Caliban, long before the play's start, and a farewell duet for Ariel and Prospero.

Before the Tempest opens well. Jon Bausor's fine set is an angled, rust-coloured screen, marked with swirls like clouds, curving like a sail. The witch Sycorax (Martina Langmann) stands in the half-light, a strange, tall figure in a ragged red dress. As she lurches from side to side, we realise that she's sitting astride Gildas Diquero's shoulders. He crawls out of her skirts, the newborn Caliban covered in black mud.

Having got Caliban born, Marston then doesn't know what to do with him. Sycorax strips off her dress, revealing more mud, and the two prowl around the stage, clutching and tottering to the screams of Jules Maxwell's score.

Marston was influenced by other responses to The Tempest. WH Auden's The Sea and the Mirror, a series of speeches for Shakespeare's characters, is one of her main sources. In After the Storm, Maxwell sets fragments of Auden's "Prospero to Ariel", sung in a breathy, tuneless drone. The effect is dreadful. Lines are pulled about until they lose all rhythm and sinew, leaving weirdly bathetic phrases hanging in the air. It isn't easy to make Auden sound half-witted, but Maxwell here manages it.

Meanwhile, Jenny Tattersall's Ariel, whose white-painted face and curls make her look like a stone cherub, flutters around Dylan Elmore's Prospero. He lifts her, wanders away from her, rocks her. Auden describes possession, loss, ambition; Marston gives us a sentimentalised relationship. In one nice moment, Tattersall stops in a low arabesque, then softens the pose, bending knee, elbow and wrist. Otherwise, the choreography lacks technical and emotional bite.

The second piece in this double bill, Asyla, is set to an earlier work by Adès, played on tape. The composer's score has a sense of structure, a toughness of purpose that Marston simply cannot match.

While the music stretches from a lean lament to crunching orchestral textures, the five dancers go through a limited repertoire of movement. They roll off one another's back, turn loosely, stretch and turn again. Tattersall dances with real attack, but none of the dancers can lift this piece. It's dance material by the yard, without texture or pattern.