The prolific Joyce Carol Oates' latest novel couldn't have arrived at a more appropriate time, emerging into a climate of heightened tension in the USA, with African-Americans protesting against police violence.

Set in New Jersey in 1987, and based on the real-life Tawana Brawley case, it's a powerful depiction of a nation divided along racial lines.

When a neighbour finds 15-year-old Sybilla Frye badly beaten and left to die in the basement of a disused factory, the girl claims she was sexually assaulted by "white cops". In a country that's already a seething cauldron of distrust, the ripples from the attack on Sybilla spread outwards, every accusation and counter-accusation bringing nothing but anger and distress.

At the centre of the story is Sybilla's mother, Ednetta, whose trust in other people depends largely on their colour. She fends off the medics who try to treat Sybilla in the emergency room and sneers at the light-skinned Hispanic female cop who tries to question her daughter about the attackers. From Ednetta's standpoint, if someone's skin isn't dark enough they're in league with the "white cops", as simple as that. The only offer of help she doesn't reject is from a charismatic preacher (a merciless parody of Al Sharpton) who intends to secure some convictions by giving Sybilla's cause national prominence. It's clear from the start that he's an egomaniac who sees both mother and daughter merely as pawns in his campaign of self-publicity, but he's black, he's a man of God and Ednetta is putty in his hands.

Oates has bravely set her novel entirely in an African-American milieu, and is presumably braced for whatever flak comes her way for doing so. Her habit, for instance, of eliding Ednetta's speech with unnecessary inverted commas gets annoying fast. And although Islam gets credit for being able to turn around the lives of delinquents, it's still a presence that lurks in the edges of the narrative, as though biding its time in a somewhat sinister way.

Still, whatever the truth of Sybilla's accusations, the racism is palpably real, and it's racism that binds the threads of this tangled, unedifying story together: poverty, abused girls, violent stepfathers, charismatic religious leaders, prejudiced cops, competing agendas. Oakes links them up in a way that, rather than seeming simplistic, acknowledges the complexities of racial division in America and ensures that, despite being set three decades ago, The Sacrifice is absolutely up to date.