When an unexpected guest visits an investment banker approaching forty, the man is shocked to realize that his visitor is a long-lost college friend. The banker’s life is unravelling, his marriage seems to be ending and his career is at its final stretch towards a collapse. Against the background of the economic recession and the fall of nations, this novel tells the story of two friends as they struggle under the pressure of class, culture and faith to control their destiny. It is a story of friendship and betrayal, infused with all the colours and variety of Bangladeshi culture.

About Zia Haider Rahman

Zia Haider Rahman is a Bangladeshi-born British novelist. This is his first book.

In Light of What We Know has been nominated for the 2014 Guardian First Book Award.

Deep into this unsettling and profound debut novel, its unnamed narrator is seized by an idea: he wants his old friend Zafar, whose sinuous, beguiling story he is listening to over the course of numerous conversations, to write it all down. "You should write a book," he says, the phrase glib and hackneyed in contrast to the sprightly erudition and distinctiveness of much of their dialogue. Perhaps, he suggests, a memoir.

"I have nothing against memoirs," replies Zafar, "but what if there's no redemption to speak of? A manual on failure and dissatisfaction, how to be unhappy, the secret to unhappiness – now that I could write." That, of course, sounds a bit more like a novel. "I don't know how to get anywhere close to my own life," he explains finally. "My drama, like everyone else's, goes on upstairs, in the head. And I don't think you can write the drama of the mind."

In the Light of What We Know is, paradoxically, a simultaneous proof and rebuttal of that assertion. By its conclusion, we've strayed far from the "drama of the mind", at least in the personal sense; the novel is filled with digressions into pure mathematics and the most esoteric reaches of international investment banking, both arenas in which theoretical abstraction and real-world consequences coexist. The novel's settings have ranged over decades from well-to-do west London to rural Bangladesh to academic Oxford to post-9/11 Afghanistan; its characters have included financiers, the English upper classes and Pakistani power-brokers. And all of this has apparently been elaborated in the service of understanding why Zafar has suddenly turned up, dishevelled and near-distraught, at the South Kensington home of his old university friend.

Its modus operandi, dependent on that initial set-up, is deceptively realistic. If someone you had once been extremely close to appeared out of the blue in a terrible state, you would do the same, wouldn't you? Bring them in, make them an omelette, pour them a whisky and ask them – gently, of course – to tell you what's been going on. It might even serve, as it does here, as a distraction from your collapsing career and ailing marriage.

But our narrator goes several steps further, installing Zafar in the top floor of his flat and holding a long series of conversations that constantly shift in tone and character, at times seeming like a therapeutic encounter, at others a confessional, a police interview, a lecture. What we have in our hands is the result of those conversations, a hybrid of the narrator's tape recordings of them, his additional recollections of useful background information, footnotes to qualify and extend the facts where necessary, snippets of Zafar's notebooks, and chunky epigraphs to begin each chapter, including extracts from Edward Said, AE Housman, Philip Roth, Joseph Conrad and James Baldwin.