In the opening chapter of Shobha Rao’s debut novel, there is a tale about an old, childless woman who has cultivated a grove of trees in her Indian village “as a way to care for something, as a way to nurture something fragile and lovely”. When a journalist comes to interview her, and she says that she sees the trees as her children, he congratulates her on having so many sons. The woman replies: “You’re mistaken, young man. These aren’t my sons… These are my daughters.”

The cultural value of sons versus daughters and the human need to find something – or someone – to care for are themes that pervade Girls Burn Brighter.

It is 2001 and in the small Indian village of Indravalli, 16-year-old Poornima and 17-year-old Savitha are facing bleak futures. Both girls have grown up in families that are economically and emotionally deprived. Poornima’s mother died of cancer and her father, who jokes about wishing his daughter were dead, is now employing the services of a marriage broker to secure her a husband.

Savitha’s family are even poorer: she and her siblings scour the local rubbish dump each day for items to sell, until Poornima’s father employs Savitha to work at his spare charkha – spinning wheel – to make saris. A friendship develops between the two girls, which soon blossoms into a profound and trusting love: “Savitha… was alive, more alive than anyone she’d ever known. She made even the smallest of life seem grand… watching Savitha, watching her delight, was like cultivating her own.”

But when Savitha is the victim of a brutal act of sexual violence, she runs away from the village, only to find herself the subject of even greater mistreatment.

Meanwhile, Poornima is married to a man whose family treat her with contempt and cruelty. What keeps both women going is the hope that they will one day find one another, a determination that takes them both from India to the US, through human trafficking, prostitution and modern slavery.

The novel is narrated in alternate sections by Poornima and Savitha, a device which encourages immersion in each girl’s story, although the narrative might have benefited from greater differentiation in their personalities. As Poornima hunts for Savitha, she repeatedly narrowly misses her by a day or two, a structural trope that, by the second half of the novel, begins to test the boundaries of plausibility.

However, Rao evokes the landscape of poverty with great skill and sensitivity: “Piles of trash also lined the huts, sniffed occasionally by a stray dog or a pig hungry enough to withstand the heat… Beads of sweat dripped down Poornima’s back. Clung like mist to her scalp.”

Both Poornima and Savitha endure multiple episodes of physical, sexual and psychological abuse. There are rapes, enforced prostitution, hot oil attacks, forcible drug-taking, amputated limbs. Many of these scenes are rendered viscerally by Rao in deeply affecting prose: “He’d grab her hair, yank her around the bed by it, slam into her with such force… bruises bloomed across her body, green and blue and grey and black, growing like nests, as if tiny birds were coming in the night to build them.”

But such is the relentlessness of the abuse that by the time we reach the novel’s final act of sexual brutality, there is a feeling of weary acceptance – by both Savitha and the reader – that this is just how life is and a sense that a less unremitting catalogue of assaults may perhaps have produced an even more powerful story.

Still, there is much to admire in Rao’s debut novel: it is a timely and harrowing portrayal of human trafficking, cultural misogyny and the battles still fought every day by millions of women worldwide.

• Girls Burn Brighter by Shobha Rao is published by Fleet (£16.99). To order a copy for £14.44 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99