The ethnic violence that devastated the central African states of Burundi and Rwanda in the 90s claimed the lives of more than a million people and created many more refugees. One of them was Gaël Faye, a French-Rwandan rapper whose alarming first novel – a prize-winner on its original publication in France – draws on his experience of being a schoolboy in Burundi as conflict broke out.

The novel starts with Gabriel, shown in a framing sequence as an unhappy office worker in Paris, toasting his 33rd birthday alone and thinking about why his online hookups always ask “So where you are from?” on account of his “caramel” skin.

The question is a cue for Gabriel’s memories of growing up in a middle-class district of Burundi’s capital, Bujumbura. Born to a Rwandan woman and a white Frenchman, he recalls stealing mangoes, gossiping about girls (“For real?! With his tongue?”) and riding his BMX bike. It’s standard coming-of-age material, until, in an escalation of the feud between the country’s majority Hutu and minority Tutsi populations, the president is assassinated, sparking civil war and – across the border in Rwanda – genocide.

Here Gabriel narrates from the perspective of his 11-year-old self. It’s a technical challenge that’s even trickier if your reader needs political context. Faye sets the scene courtesy of “endless explanations that nobody had requested” from Gabriel’s father and Gabriel’s habit of eavesdropping, which allows the novel to discuss how violence kicked off despite “the presence of so many UN peacekeepers” in Rwanda.

But a narrator with limited insight should be more than simply a problem to work around. When Gabriel says Burundi is “full of “invisible rifts, sighs and glances” that leave him puzzled over “the meanings behind silences, about what some people left unsaid”, Faye seems to squander the dramatic potential that a child’s point of view might bring. Perversely, Gabriel’s capacity to articulate his own ignorance militates against enacting it; Faye is telling, not showing. And by the time Gabriel draws an analogy between Burundi’s politics and its position in the Great Rift Valley – “beneath the calm appearance... this poisonous lava, the thick flow of blood, was ready to rise once more. We didn’t know it yet, but the hour of the inferno had come” – you feel the boy’s voice has escaped Faye’s control.

For the most part Gabriel hears news of the increasing bloodshed with bewilderment, an effect of his cultural dislocation. His Tutsi mother considers him “white”, mocking his accent if he speaks her language, and he’s largely unmoved by the ethnocentric rabble-rousing that fires up his well-to-do peer group, eager to go “home” to Rwanda to fight – an aspiration that provides unlikely comic relief when one boy starts hoarding weapons to general disbelief (“You’ve gone and bought grenades, you’re storing them next to a fillet of frozen beef”).

But there’s nothing to laugh about by the end. This sharp shock of a novel implies that, amid terrifying social breakdown, innocence isn’t easily claimed, as the narrator’s memories turn confessional and he becomes a participant in the violence. If you sense Gaël Faye named him Gabriel to suggest they share DNA without being identical, the climax leaves you hoping for his sake that there’s more than just a syllable’s difference between them.

• Small Country by Gaël Faye is published by Hogarth (£12.99). To order a copy for £11.04 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99