In Samuel Beckett's first novel, Dream of Fair to Middling Women, James Joyce's daughter Lucia appears as the discarded lover of the book's hero. "She remains," writes Beckett, "whatever way we choose to envisage her, hors d'oeuvre".

In Samuel Beckett's first novel, Dream of Fair to Middling Women, James Joyce's daughter Lucia appears as the discarded lover of the book's hero. "She remains," writes Beckett, "whatever way we choose to envisage her, hors d'oeuvre".

Lucia Joyce - who worked as a modern dancer in 1920s Paris, first became a psychiatric in-patient in 1934, and spent 30 years in a Northampton hospital - is a marginal, phantom presence in the biographies of others. Cropped, her photographed face is a monochrome adjunct to more colourful reputations. Now Carol Loeb Shloss has set that image into fractured and haunting motion.

Photographed for an identity card in 1951, Lucia's gaunt, incarcerated profile seems to have turned back, in middle age, to look on more mobile versions of herself. A mid-1930s snapshot sees her already distraught, but gesturing hopefully to camera. In childhood photographs, she is a blaze of light at the centre of the Joyce family's shabby exile. Then she is a dancer, posing in tortuously elegant attitudes, poised between classical statuary and modernist mechanics.

Somewhere among those snapshots is the seed of another sort of book, a more speculative essay that would let the image of Lucia condense into the enigma she seems to have felt herself to be. But Shloss has other ambitions for her cryptic subject. Lucia's flighty talent and etiolated life are here inflated to the status of other gargantuan lives. If Lucia sometimes fails to bear the strain of this athletic academicism, Shloss's best metaphor still remains the dance. She is at her most acute when elaborating affinities between Lucia's physical alphabet and her father's dancing words.

Lucia Joyce spoke "a curious abbreviated language of her own"; but it was the words of others which condemned her to a sanitised half-life. She was often, undoubtedly, unwell, and in a sense the story of her real and metaphorical straitjacketing is unexceptional. At her death in 1982, at St Andrew's Hospital, Northampton, she was simply one of many lost to psychiatric ignorance, institutional obtuseness and familial shame. But the details of her gradual erasure are nonetheless intolerable, and her "madness" (as Joyce insisted until his death) never proven.

"I never had a chance! I was cumbersome, in the way," she recalled. Shloss persuasively unravels the skein of misreadings that doomed her: the well-meaning insistence of acolytes like Maria Jolas and Paul Leon that Joyce should be left in peace to finish Finnegans Wake; the strange distance of Nora Joyce from her daughter's fate; the callousness of brother Giorgio, who would have locked her up much earlier.

Lucia drifts, a wraith at the mercy of conjecture. Shloss's mind is often accosted, not to say violently mugged, by unsupportable fancies: the spectres of early incest or abortion. Despite the occasional gush, however, she has succeeded in channeling the drowned life of Lucia into something like its proper course.