Blonde Roots by Bernardine Evaristo

Young, gifted and whyte: life in Great Ambossa

History is subjective. With fact as its backbone, its relationship to fiction is that of the stern and virtuous great aunt to a muddy kid. Africans were enslaved by Europeans for 400 years. The British Empire was the granddaddy of economic and human exploitation during that time. It takes a particularly brazen kind of muddy kid to argue with this. The facts of the transatlantic slave trade are accepted, then either shrunk from or built upon, such as in Edward P Jones's surprising depiction of a black slave owner in The Known World.

In her new novel, Bernardine Evaristo, never one to shrink from an experiment, has taken her boldest step to date and turned the whole thing on its head. She imagines it was Africans who enslaved Europeans – namely the spirited daughter of a family of English cabbage serfs, Doris Scagglethorpe. The empire was not a tiny big-headed island near Calais, but a similar one called the United Kingdom of Great Ambossa off the coast of "Aphrika". In Evaristo's muddy hands, history is Playdough.

The 11-year-old Doris is captured while playing hide-and-seek with her sisters. She's put in chains and finds herself in the hold of a slave ship, where she experiences the horrors of the Middle Passage, the darkness and disease, the rapes and suicides, the torturous punishments for weakness or revolt, and the feeling of lying next to a corpse for days. Her fate from there is a step up from the average "non-achieving, low-flying slave". She begins her new life as mistress and playmate to a spoilt Ambossan brat who teaches her to read and write, then is posted as PA, or "house wigger", to import-export boss "KKK", Chief Kaga Konata Katamba I, or Bwana, whose estate lies in "Londolo's" most affluent district of "Mayfar". Her hours are Monday to Sunday, 12 am to 11.55 pm, unpaid, with overtime when necessary.

Evaristo has said that she always wants to have it easy and write a straightforward prose novel but her intentions get thwarted en route. This time she has managed it, the novel-in-verse poet peeking through in beguiling description – a character with "the stoop of a thin tree blown forwards by a gale" - and sections, particularly of high drama or strong emotion, where the text reverts to the fleshy one-liners of her previous form.

A sizeable suspension of disbelief is required as fair, stringy-haired and thin-lipped Doris takes us in vivid detail through her people's inferiority issues about belonging to the alleged physically, intellectually and morally debased "whyte" race, but one of the best things about this book is its bittersweet, riotous humour. In the "Vanilla Suburbs" of Brixtane and To Ten Ha Ma, where a free whyte Diaspora has already emerged, natural blonde tresses are replaced by Aphrikan weave-ons, nose-flattening jobs are quite affordable, and tanning studios rife. There are civil-rights protesters and SUS laws, and the security guards are always white, not black. As she did in her smouldering verse novel of Roman London, The Emperor's Babe, Evaristo has brought the historical into the contemporary zeitgeist (of self-help books, middle-class neuroses, knife-carrying youth), creating her own skipping vernacular, and in the midst of all this jive making serious comments about the construction and irreversible effects of racism.

Running through these pages is not just a feisty, hyperactive imagination asking "what if?", but the unhealed African heart with the question, "how does it feel?" This is a powerful gesture of fearless thematic ownership by one of the UK's most unusual and challenging writers.

Diana Evans's novel '26A' is published by Vintage