Constance, By Patrick McGrath. Bloomsbury Circus, £12.99

Patrick McGrath's father was medical superintendent at Broadmoor, the high-security psychiatric hospital. McGrath's legacy was a fascination with psychiatry that has coloured his dark, unsettling fiction. The disturbed and unstable have loomed large in novels from Spider and Dr Haggard to Ghost Town and Trauma.

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In Constance, McGrath revisits two themes from Trauma: the disturbed nymph, and sibling rivalry. Constance and Iris are very different sisters who grew up in a dilapidated Gothic building in the Hudson Valley with their doctor father. Constance is convinced she is a victim of monstrous cruelty from their father, and is unable to enjoy the love of her husband, Sidney, who wants to cherish her. Iris is a vivacious young woman but is deeply vulnerable. The novel is dually narrated, some chapters by Constance, others by Sidney.

Constance's sourness and envy are apparent in her readiness to put Iris down and her lack of sisterliness. She betrays Iris, but feels little guilt on a conscious level. Habituated to the role she has created for herself as victim, she is unable to respond to anything positive. She sees Sidney as a controlling pedagogue.

Then comes a shattering revelation. Constance does have a reason to feel aggrieved. Is it sufficient for her egocentric, curdled outlook? And she is also capable of giving love to Sidney's son from his first marriage. Whether Constance is seen as a self-pitying narcissist or a true casualty of circumstance is up to the reader. The picture is complicated by the implication that Constance hears voices: perhaps she is suffering from paranoid schizophrenia and is therefore not responsible for her negativity.

The garbage-strewn streets of 1960s New York provide an apt background to the disintegration of Sidney and Constance's relationship. The prose here may lack the passion of some earlier work, but this is still a fascinating examination of the effect of childhood trauma on the adult, and the folly of sinking into lifelong victimhood.