I'll Take You There by Joyce Carol Oates

She calls herself Anellia, but we never learn what her real name is. She tries on identities like clothes, then tears them to pieces when her disguises fail her. In fact, she disguises herself in order to be unmasked.

The protagonist of Joyce Carol Oates's new novel is the youngest child and only daughter of a poor farming family in upstate New York. Brilliant but isolated, she has been rejected by her father and three brothers because her mother died giving birth to her. When her father turns travelling man, she is left to the mercies of her macho brothers – whom she nevertheless idolises.

She describes herself as belonging to another species ("I was a freak") and loathes her tiny undeveloped body. A scholarship student wearing charity-shop clothes and reading Spinoza, she is pledged to Kappa Gamma Pi. The "Kappas" are the most glamorous, wealthy and empty-headed sorority on campus, their single aspiration to become engaged before graduation. They are also racist bigots. Yet Anellia craves their acceptance and that of their housemother, Mrs Thayer, who is a paragon of propriety.

Anellia was pledged to these unlikely sisters only to help them with their term papers. Yet she goes into debt to pay her rent and is soon grubbing food from bins. At the Kappa alumnae reunion, a harrowing setpiece, she is discovered rifling Mrs Thayer's closets and publicly confesses to being part-Jewish: and therefore ineligible for Kappa membership.

Anellia's reckless bravery goads her into the sin that will guarantee her beloved's permanent alienation. But her ensuing shame and self-loathing are a process of purification in which, by casting herself as the penitent, she is freed from "the perverse romance of addiction". Yet Oates never permits Anellia's anguished search for her mother and siblings to slide into Freudian cliché. It is too raw ever to feel stale.

Once again, Anellia chooses the most dangerous and inappropriate love object: an erudite and elusive philosophy student, Vernor Matheius. She follows him with canine devotion, and gradually he appears to return her love. As a mixed-race couple in the early Sixties, they are resented, abused and marvelled at. She becomes the "nigger-lover". Though their affair parallels the rise of the civil rights movement, Vernor disdains politics, refusing to "step into history".

When Anellia commits an unpardonable offence against his privacy, he brutally drives her away. She seems to seek punishment, but penitence is also liberation. Each frightful rejection brings a clarification of her true goals. She steps into history and becomes a civil rights activist and, later, an author.

Oates is an inspired writer, and a formidable psychologist. She has a thrilling way of grasping an emotion, wasting no time in judicious rumination but launching herself straight at the aching heart of the matter. This lends her writing its urgency and excitement. Where is the pain? Where is its source? I'll take you there. And you go willingly.

The heroine's drive west worried me slightly, since in most American novels it is the signal of self-discovery. Instead, it leads to her ultimate transgression. She may no longer be Anellia, but she is still compelled to penetrate another's secret; to see and know that which is forbidden.