Whodunnit? No one, yet. Frances Fyfield on a judge's dread; Your Blue-Eyed Boy by Helen Dunmore Viking, pounds 12.99
Helen Dunmore is a winner of the Orange Prize and an acclaimed author of five literary novels as well as short stories (The Love of Fat Men, now published in paperback), poetry and novels for children. Since the cover here tells us that this novel features blackmail, with a judge as the central character, there is an immediate suggestion of a departure into the more populist area of the crime thriller. Oh, the woes of categorisation for books and authors who defy such a thing, as Dunmore does. Yes, there's a judge; yes, there's blackmail of a kind, but any expectation of cheap cut-and-slash will be disappointed.

What this blue-eyed boy has in common with the best of crime thrillers is a brooding sense of menace, although the central threat is not death, but moral carnage. Comparisons with the crime genre are not odious. The house in which Dunmore sets her tale is the kind of house where a murder might well occur; an isolated house surrounded by sea and marsh, which begs to feature in a shock/horror headline.

Inside it and inside the actions of her characters, Dunmore explores the slow-burning preliminaries to the kind of violence possible in the most ordinary and controlled of lives. The house itself is a fine deceit; it looks solid, but it is not. Simone is a late-thirties, county-court judge with two young sons, a husband and track record of modest success which make her enviable. She has done everything right; she is honourable, compassionate and strong, a virtuous woman whose virtues can never be quite forgiven by her dependants because her self-control is too complete and she is too strong to be pitied.

The family looks prosperous, as befits her status, but husband Donald is on the verge of emotional and financial bankruptcy. They have moved to the edge of the sea and a life of poverty, to pay his debts. Simone does not judge him; she judges for others and refuses to allow the existence of the breaking-point.

Into this scene of shimmering tension there enters the blackmailer. But this is not a crime novel: there is no crime. Simone has done nothing despicable other than to have an affair with a young Vietnam veteran in America 20 years before - her preliminary to a responsible adult life, his to one of mental instability.

The affair, however intense, was not a crime, but the photographic records of it could blow a fragile marriage and the family income into the sea. The lover - older, fatter, disappointed, jealous of her success, obsessively in pursuit of a faded dream - follows his letters with his presence. Although he is weak and insubstantial, his power over them is out of all proportion.

The first-person narrative is as cool and sensuous as Simone herself. Dunmore is chillingly adept at the portrayal of lust and its close cousin, revulsion; equally adept in the evocation of the bleak landscape that comforts Simone's existence while alienating her family.

The court scenes, a sideplay to the narrative and acted out under the scrutiny of a sinister usher, describe with uncomfortable precision the isolation ensured by any position of power exercised with humility. Simone knows the power as well as the powerlessness of the law. It cannot help her or save her children; the terror springs from the fact that nothing can, except herself. It is her burden to retain responsibility when everyone else abnegates it - an ultimate in loneliness.

What make this novel so convincing is that it takes responsibility for itself, poses no solutions and leaves all the lives, bar one, unresolved. An impressive case of art mimicking life. The sea closes over the scene; the murder might still be waiting to happen.