Guy Gunaratne is sipping lemon and ginger tea at the end of a larynx-taxing week recording the audiobook of their latest novel, Mister, Mister. The book is set partly in east London, where we’re meeting before they catch an evening flight home to their wife and two young children in Malmö, Sweden. For the author of 2018’s Booker-longlisted In Our Mad and Furious City (or Mad, as they handily call it), the zigzag itinerary has become a routine: the new book, initally sparked by the controversy surrounding Shamima Begum, was completed during a three-year fellowship at Cambridge, which they took up in 2019 shortly after becoming a father. “The university gave me a room and a desk; no lecturing, just writing.” Then the pandemic hit. “It was tough. When I was younger I dreamed of a project that would transform you – where you’d be a different person at the end of it – and that’s certainly been true of this, but I wouldn’t want to do it again.”

A difficult second novel, at least for the author, Mister, Mister is a rollercoaster coming-of-age picaresque, set against 40 years of bloodshed in the Middle East, from Desert Storm to Islamic State, and narrated by a fatherless young Londoner, Yahya, half-English, half-Iraqi, raised in a refuge by Muslim women before becoming a poet-preacher whose tub-thumping lyrics echo dangerously around the world in an age of keyboard warriors only too ready to step out from behind the screen. The book starts with Yahya held as a terror suspect, having recently returned from Syria – and he’s just sliced off his own tongue, spilling his life’s twists and turns solely in writing for the eponymous Mister, the shadowy British official quizzing him.

Akin to a retooling of Charles Dickens’s Great Expectations for the 9/11 generation, it might fox anyone expecting a retread of Mad, narrated in a testosterone-fuelled demotic by three teenage boys (as well as their migrant parents) caught up in race riots on a north London estate after a shocking murder resembling that of Lee Rigby. While some of that novel’s themes remain – as does the buttonholing linguistic verve – Mister, Mister is more layered, more slippery, almost mirage-like at times, concerned with the inadequacy of language and identity while glorying in the infinite bounty of storytelling, always teasing and rug-pulling as to how and why Yahya ended up where he is.

“The book started off very modest and small but Yahya’s voice kind of broke everything and I had to follow it,” says Gunaratne, a former documentary film-maker. “It became a sort of refusal, not just of Mister’s accusation, but of coherent individualisation. In the traditional life-and-times tale you have a self forming itself – a penniless orphan in Dickens becoming a gentleman, step by step – but with Yahya, it was the opposite: an unravelling, just him undermining and evading everything with a performance of multiple selves.”

Mister, Mister’s afterword tells us the book was brewed in the six years after the Brexit vote, a tumultuous period in which Gunaratne, 39, was likewise “making new determinations about my identity”. When I ask what that means, they pause, not for the first time in our two-hour chat. “It’s difficult to articulate. It isn’t a major key in the novel – it was a major key in the writing – but Yahya writes about desire from a place that exceeds normative understandings of gender. I realised I probably had to talk to the people closest to me about my own fluidity, or queerness. But it’s a private thing. The decision to use the identification non-binary and they/them pronouns has offered a way of feeling better understood, even if it’s still an approximation.”

New fatherhood at long distance while re-evaluating “parts of myself that had gone unaffirmed” and scrolling through (say) images from Abu Ghraib to research Mister, Mister – all of it alone in a new city during a pandemic – unsurprisingly had its lows. But Gunaratne is only grateful for the fellowship, as well as the support of the writer Ali Smith, a colleague. “That Abu Ghraib section took a toll. I thought, let me check out and go and see Ali. She put her hand on my heart and said: ‘You’re doing the thing you’re supposed to be doing. Trust it.’ I wrote it that night literally under my desk.” Did Gunaratne ever consider simply avoiding the subject? “No. I didn’t have a choice. My documentary work involved interviewing people who would tell the most horrific stories. It teaches you to listen but also not to flinch.”

Gunaratne, born in London to Sri Lankan parents, speaks carefully with an easy stillness that I suspect was honed during those years of listening to traumatised interviewees in trouble spots around the world in their 20s. Always writing stories as a child, they turned their hand to screenplays after a film and TV degree at Brunel University under the spell of Jean-Luc Godard and Martin Scorsese, the subject of their dissertation. Gunaratne isn’t sure where they found the courage to jet off to film documentaries about formerly abducted child soldiers in Uganda or journalists facing death threats in Guatemala, but what eventually became clear was that the latitude afforded by novel-writing held greater allure. “I take a long time to form an opinion politically; it’s why I don’t tweet so much. I want to be able to simmer on a thing, and in a novel you can perform those kind of debates and never settle in one place. In documentaries, there was always a point; in a novel there’s ambiguity and oscillation.”

Gunaratne was going to leave In Our Mad and Furious City in a drawer until their wife, a fellow documentary-maker, prodded them to submit it to agents. A two-book deal (Mister, Mister fulfils the contract) and a rapturously received debut followed, but Gunaratne still wonders if Mad was, well, mad enough. One of its intersecting narratives involves a Windrush migrant, Nelson, who stays stoic in the face of racism as his friends turn to violence; Gunaratne was thinking of their father, who spoke of having to get on with things after he came to London from Sri Lanka in 1951. “That wasn’t the temperament of myself and a lot of my friends – it’s not something you swallow – but my father had this sense he had to earn his place,” says Gunaratne. “When I hear my parents talk about that sensibility, it feels conservative to me in a very ugly way. I hope there wasn’t a feeling of conservatism [in the book]. Having Nelson view the violence he witnessed and then choose a different way… There is an evasion there I don’t find entirely satisfying. There was a narrative move left on the table.”

What does Gunaratne make of the arguments around Granta’s latest once-a-decade list of best young British novelists under 40, which Bernardine Evaristo (in a since-deleted tweet) said was “whiter” than it’s ever been when British fiction is “browner” than it’s ever been? “Any list with Yara [Rodrigues Fowler] and Olivia [Sudjic] on it, you can’t beef too much with,” says Gunaratne, after probably the longest pause of our chat; later, I receive a characteristically rich and thoughtful message adding that they’re “desperately tired” of identity-based arguments and the “ugly commodification [that] occurs when one group of writers are pitted against others”.

When we speak, Gunaratne says with a smile that these are “publishing questions” unrelated to art or creativity. They laugh to recall the assumptions that lay behind a question they were once asked about whether writing In Our Mad and Furious City had been “a deliberate political move to put these characters in literature”. They recall, too, how sure people were that the novel’s touchstones were Salman Rushdie, Hanif Kureishi and Zadie Smith; important influences, Gunaratne agrees, but then so were William Faulkner and James Kelman. I’m reminded that Gunaratne once wrote of how reading Karl Ove Knausgård and Samuel Beckett helped them feel closer to their father. “I know many writers, writers of colour mostly, who seem to believe certain writers aren’t for them simply because of where they think everybody else has positioned them,” they tell me. “But I’ve never felt denied Dickens, TS Eliot and Woolf. Shakespeare is mine. Dickens is mine. To imagine into a tradition that’s never imagined me represents only possibility.”

• Mister Mister by Guy Gunaratne is published by Tinder Press (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply