Sameer's life is going well. The 26-year-old Cambridge graduate is a rising star at his London law firm, he lives in a swanky penthouse flat in Clerkenwell in central London, and plays as hard as he works - and he works very hard. It's enough to go to a young man's head, but his feet are kept on the ground by two old mates - Jeremiah and Rahool - from his home town of Leicester, who, like him, are making their way in the capital.

The three amigos hang out, listen to the rapper Dave's Psychodrama album and drink vodka. They're celebrating Sameer's career-advancing offer of a move to Singapore, Jeremiah's new job at a recording studio, and Rahool's decision to… go back to Leicester? And so begins We Are All Birds of Uganda, the debut novel by Hafsa Zayyan, joint-winner of Stormzy's #Merky Books New Writers' Prize. On the evidence of this book, which is set in England and Uganda, she is an exciting new literary talent.

The author shares some of her protagonist's biographical details. She too went to Cambridge University (and Oxford), became a lawyer, lives in London, and was offered a posting to Singapore. And, like Sameer, she is from an immigrant family: her parents are Nigerian and Pakistani, his are East African Indians. But this is not her story, it is his. She went to Singapore, he has yet to decide to accept his offer. In the history of dramatic plot-lines it is not the most arresting, but it does serve the purpose of providing a gateway into the main themes of the novel.

The issues and subjects it takes on are big: British, South Asian and African racism, religion, the past, acceptance and belonging, identity, immigration, capitalism, multiculturalism, family values, generational differences, the notion of success. All are explored with great intelligence and sensitivity - But at a cost. The novel reads as if it is topic-led rather than story led, the facts more important than the fiction.

The characters feel small and thinly drawn - doing their duty to maintain structure and illustrate a thematic point, rather than being the point. They don't appear to have been allowed to take on a life of their own, to surprise us; to surprise the author. Sameer is a nice bloke with some serious life decisions to make, but is, as protagonists go, a tad dull. There is no shade to his light. The same applies to Jeremiah and Rahool, who are little more than cameos. Family and relations follow well-worn paths, dividing along generational and cultural lines. There is no devil in the detail. All of which makes the first two-thirds of We Are All Birds of Uganda quite slow, but stick with it and the rewards come as Zayyan's writing finds the lightness and fluency of a much more experienced novelist.

Having been curiously incurious about his past, Sameer finally discovers his sense of identity and purpose when he engages with his own personal history, a history that is drip-fed to the reader in a series of short, interlaced chapters, which take the form of letters written by his grandfather to his deceased first wife. They are poetic history lessons contextualising the circumstances that led to Sameer being brought up in Leicester rather than Kampala, where his father was born.

The letters cover the period between the end of World War Two to the decade after Idi Amin's expulsion of South Asians from Uganda in 1972. It is an epic novel in terms of historical, geographic, and cultural scope and has much to recommend it: the tone, the structure, the ambition, and the clarity that enables the story to cover so much ground without ever becoming confused or lost during its 360-pages.