Indian cinema is recognised across the world as the exporter of Bollywood movies; one of the most mainstream of genres. In Love Sonia, the debut feature from Tabrez Noorani, the music and colours of Bollywood are shown on crowded buses and in the back of brothels. It’s like Noorani is showing the reasons why millions want to escape into that vibrant fantasy – and in the tortured world he paints, filled with poverty and prostitution, can you blame them?

Sonia’s (Mrunal Thakur) world is turned upside down when her patriarchal father (Adil Hussain) sells her sister Preeti (Riya Sisodiya) into slavery. After learning Preeti’s destination, she travels to Mumbai to save her sister – only to end up being captured as a sex slave.

The father (Adil Hussain), the mother (Kiran Khoje), and their daughters Sonia (Mrunal Thakur) and Preeti (Riya Sisodiya)

There was a real danger of Love Sonia being exploitative, entirely focused on shocking the audience rather than telling a story. But Noorani manages to show the horror, the darkness, and the overwhelming pain of working as a sex slave without feeling gratuitous.

The film starts like a fantasy epic: in a rainless desert, no food growing, humble surroundings, sisters Sonia and Preeti dreaming of a big life in Mumbai. All the while, their father’s Job-like suffering at reaping no harvest manifests into hatred for his daughters.

Once Sonia penetrates the heart of Mumbai, entering a brothel, the fantasy dissipates – filling her with a confused darkness. Her innocence is stripped away like sharp fingernails scratching on skin, and all we can do is watch the trauma she’s made to endure.

Sonia and Preeti start from innocence, then plunge into darkness

She’s made to do unthinkable things while keeping her virginity in tact, managed by a Freudian dream of a pimp (Manoj Bajpayee) who refers to his workers as his ‘daughters’. He’s intent on keeping them safe, but they’re never allowed to leave – the atmosphere turning almost unbearably claustrophobic.

Sonia’s tale of survival reaches from Mumbai over to Hong Kong and then to Los Angeles, trapped in the thick of that experience. This journey is comparable to that of Steve McQueen’s 12 Years A Slave where submission is inescapable and time, from the character’s point of view, is impossible to determine. It’s harrowing, but Sonia and her relationship with Preeti provides enough warmth to bear the terror.

Love Sonia drifts into something of a charity advert by the end, the film being a vehicle to raise awareness, but it’s no less emotional. Screenwriters Ted Caplan and Alkesh Vaja leave the film depressingly unresolved, foregrounding both the story’s dreaded uncertainty and it’s hope. Sonia is filled with darkness, but she’s always able to see the light.

Love Sonia will be released in UK cinemas on 25th January