As themes to debut novels go, so-called "gendercide" - a controversial cultural issue in certain countries where the preference for sons is so strong that baby girls are killed - is not usually the stuff of best-selling, award-winning books. Until now. Kishwar Desai brought the issue to mainstream literature, winning the Costa First Novel Award earlier this month for Witness the Night - which begins with a mass killing of a family who have, it soon becomes clear, practised sex selection themselves.
Tomorrow, the novel will be up against the likes of Maggie O'Farrell's The Hand That First Held Mine to win the prestigious Costa Book Prize. And Desai admits she's been "overwhelmed" by the reaction.
In her colourful career, Desai - who has homes in India and the UK - has been a documentary filmmaker, a journalist and a news anchor. She's run her own production company and even a television channel. So a documentary or essay about gender-based infanticide would have been the obvious choice for this social campaigner, who is married to the British economist and Labour politician Lord Desai. But she came to the conclusion that, if she really wanted to change things, fiction could be more a more powerful tool.
"About two years ago I realised that television wasn't what I wanted to do any more," she says, relaxing after yet another photo shoot in India. "It was becoming so superficial - everything was celebrity-orientated, while the important news stories were only getting two minutes. With non-fiction you can talk about facts, but when you write a novel you deal in emotions - and that was key to me.
"Talk to journalists in India and they will tell you how frustrating it is to write about the same issues year after year. Things are not changing. So I thought I should approach gendercide from a different angle. My idea was that if I could get readers to connect emotionally with what it is to be an unwanted girl child growing up, then there could be some change that could come out of that. I wanted people to feel the anger that I felt - and to think that, in some small way, that has come true is a huge reward."
And yet the reason Desai's novel has won this high-profile award isn't because the judging panels are simperingly handing out prizes to authors highlighting worthy causes. Witness the Night is an intriguing read. Desai argues that she didn't set out to write a crime novel ("I didn't even know it was one until my agent told me," she laughs), but it follows many of that genre's conventions.
A teenage daughter, Durga, is found alive amid the carnage of the murders, and is immediately accused of the killings - but it takes the unconventional methods of Simran, an outspoken social worker, to explore the actual circumstances of the case. Desai wrote Witness the Night in just a month as an experiment - which is sometimes evident - but despite the subject matter it's certainly enjoyable to follow Simran's increasingly desperate attempts to untangle the layers of deceit.
Simran's failings - she's acerbic, dismissive of her mother, a heavy smoker - make her great fun; not light relief exactly, but certainly somebody to root for when everything else seems to have a darker side.
"I think working in television for so many years drummed it into me that this needed to be a good read first of all," admits Desai. "I couldn't afford people to switch off because this is such an important subject. So I had to ensure this wasn't a book about victims, for people to say 'oh, these poor women in India'. I wanted them to feel anger rather than pity. The only way to do that was to have a protagonist who similarly feels anger, who wants to rip the establishment apart, who doesn't have respect for anyone or anything."
In that sense, it feels a little like Simran is a natural extension of Desai. Can she see herself in this likeable, independent woman who won't take no for an answer?
"Oh, I do wish I were like her!" she giggles. "I think through writing you can do things you could never do in real life, so perhaps through Simran I'm living the life I would have liked to have led. I don't have the courage she displays, though, so the only way I can focus attention on, say, the horrible gender bias in India is through my writing. But I do think women in India need to be like Simran, and take things into their own hands."
Witness the Night, then, is undeniably a political book. It shines a light on a country Desai says is in the grip of an extraordinary paradox: one of the most vibrant and fast-growing economies in the world and yet also one in which women often seen as both second-class citizens and ruinous economic liabilities.
Millions of women, she says, have gone missing and millions more live lives of degradation and humiliation. Yet one of India's most famous prime ministers was the assassinated Indira Gandhi, and the current president is also a woman. So for Desai, it was crucial that the book should ring true if she wanted to highlight some of the issues that fill Indian newspapers daily.
"The linkages and the narrative are a fiction, but the rest, I'm afraid to say, is all true," she says. "The book is a conflation of two real events: a woman came to my office in Punjab who learnt her parents had given her opium when she was born - it's a very common way to kill babies.
"She survived - but her life was completely traumatic because she grew up in a household where she knew her parents were her would-be assassins. I kept thinking about that, and then I read about this girl in Bengal who had been accused of murdering her entire family. So Witness the Night wasn't made up in that sense. The two things came together in my mind when I sat down to write."
And despite painting such a dark picture, she's adamant she wrote the story because she loves India - "you can't not do so if you live here," she says. Indeed, the book received very good reviews in India itself, with many commentators saying it should have been written years ago. It's gone on to have a global impact, enjoying translation into many languages and, of course, winning prizes. So is she encouraged that such a positive reaction may actually have any effect on the issues she raises?
"Well, yes, but because of the subject matter I do also feel a real sense of loss every time I think about it - the actual issues have no joy or happiness attached to them. It's great that gendercide is being spoken about, but there needs to be more than just discussion or awards for me. It needs to save the lives of a few baby girls."
To achieve that, Desai says, women in India must be educated and accepted in the workplace - all of which she believes should be possible when the president is a woman. And such simple, straightforward realism extends to her debut novel, too. One of the reasons it won the Costa First Novel Prize, I suggest, is that it might be a crime novel, but it doesn't stick entirely to the conventions of that genre. The loose ends aren't tied up in a memorable "whodunnit" scene. The truth, you sense, is more complicated than that.
"Exactly. That's what I wanted to say. I see people getting away with, well, murder all the time. That's why a neat little ending where everyone lived happily ever wouldn't have worked. Because, here, they don't."
Witness the Night (Beautiful Books) is out now. The Costa Book Awards are on Tuesday. Visit www.costabookawards.com for information on the other nominated books.