An early life spent among the mentally ill has seen to it that in a McGrath fiction trust is perilous. The reward - as anyone crossing swords with the Blood and Water collection or the novel Spider will testify - is a fiction of perception; the narrator's troubled eye sees nothing and everything as it is.

Haggard addresses his sorry tale to Vaughan, the fighter-pilot son of the only woman he ever truly loved. He finds himself incapable of relinquishing the brief all-consuming months spent with the senior pathologist's wife, his dismantled life now little more than a shell of painful melancholia. And yet through the curiously androgynous boy there is a rekindling of memory, and a new, altogether more bizarre passion engulfs the doctor. McGrath's novel is a love story, albeit from behind eyes addled by morbid introspection and morphine addiction.

Dr. Haggard's disease itself is a definition as flexible as his own fanciful self-deceit. Initially eroticism, McGrath weaves an intricate web of love and obsession gradually absorbing reader and doctor alike; slow-burning infatuation and explicit, increasingly hazardous coils leading to inevitable frustration and punishment.

At once the disease becomes distress and grief at the void of his life when he finds himself inexplicably abandoned in Elgin, the country practice to which he flees.

And finally, the disease to which Haggard determines to lend his name, the bizarre malady he discerns burdening Vaughan, one drawing him progressively closer to the boy as potential saviour; but one with inevitably tragic and strangely liberating consequences.

The book is at once more approachable, less fractured than his exceptional, galvanising examination of the schizophrenic Spider, and yet one equally blessed of the incipient nastiness that fuels all his best writing. McGrath binds the unsuspecting visitor into Haggard's singular Neo-Gothic with eroticism and hunger; hooked, he counters with obsession and psychosis.

Magnificently written, it brims with the brutally picturesque: the cinematic Battle of Britain apparently rages solely in the skies above Haggard's precipitous home; his shambling, agonised gait; the monolithic Victorianism of the hospital. Coolly ingenious, deceptively lucid, the book is an intensely readable yet uncommonly intricate portrait of blind infatuation propelled toward self-destruction. A match, then, for the exceptional Spider, and very possibly a masterpiece.