It's often said that a dependence on modifiers is the sign of a weak writer.

But Romesh Gunesekera is a man who knows how to use an adjective: "When she put her fingers to her lips, she nearly swooned. Here at last was the true nectar of the south she had so longed for: strong and sweet, amniotic and electric, laced with a hint of the immortal."

In 1825, Lucy Gladwell leaves England for Mauritius. Her parents are dead and she's to live with her buttoned-up aunt Betty and uncle George, the usual choleric, alcoholic, riding-crop-wielding official, in this newly British place. Lucy is a forthright, well-read but lonely girl, whose only companions in life have been books, such as Thomas Moore's Lalla Rookh and Keats's Endymion; books that may or may not be good for you if you are a forthright but lonely girl. So far, so 19th century. But in this blisteringly lucid novel, it's as if Jane Austen, John Keats, Charles Dickens and even William Burroughs have clubbed together to render a masterful double-take on the 19th century's own ideas of romance and empire, rendered in a colossally skilful, flexible hybrid of the best of English prose and prosody.

Gunesekera lays out a recognisable situation: Lucy is introduced into society, her guardians helping her negotiate the complex world of Mauritius – part British, French, Ceylonese, Indian, African – and hoping she will find a mate. British would be best. French, maybe. However, Lucy quickly falls in love with Don Lambodar, secretary to a Ceylonese prince under house arrest on the island. Don is equally taken with her, and one of the real, multilayered delights of this novel is watching two hyper-romantics deal with burgeoning love and the demands of Victorian romance.

Trouble's afoot, too, in the shape of the inhuman treatment of those on Mauritius who are not white – which is just about everybody. So having set up this quite familiar tableau, almost the stuff of lurid bilge, Gunesekera sets about twisting it, playing with it, and subverting it with a great deal of wit and subtlety, while maintaining his own rapt attention to the entire history, it would seem, of English style.

For example, a po-faced discussion between Lucy and her aunt about "the tragic consequences of miscegenation", in a botanic garden full of genital-shaped fruits and vegetables, is interrupted by the figure of Jeanette, a mass of giggles and jiggles whose blushing is mapped by the author with the zeal of a hydrologist. And in one of many linguistically astonishing scenes, Don Lambodar nervously attends his first real "English tea" under the influence, he realises, of a little too much opium. This goes from a risible scene out of Shaw to a Hunter Thompson hell in the poor suitor's head, as he struggles with civilised conversation, gagging on tea cakes made of saffron and concrete, being squawked at by a mynah out of nightmare. He finally reels out, convinced he's tripping over his foreskin, and lands in a bed of prize geraniums. Put that in your bodice and rip it.

Seriously and movingly, The Prisoner Of Paradise contains a very modern message: a plea for the book. It has as much to say about writing as it has about love and colonial misery – words are one of the chief attractions between Lucy and Don (in fact they're the only two on Mauritius who give a damn about books other than the Bible): "She would wonder - how it was that the markings of a nib, or the scratches of a stranger's sharpened quill, either by itself or through reproduction in the more formal pressed letters on a page, could result so unerringly in a blue ribbon of sea, a strip of white sand, a red boat -" As do Gunesekera's words, and his Mauritius. But in the face of opposition, Don Lambodar and Lucy Gladwell manage to write themselves on, into, each other. They are determined to remain known, because of simple acts of writing.

What is a real novelist's proper approach to history? Certainly not to detail how tightly laced the ladies were at which fete and exactly what kind of ices were served, and Gunesekera masterfully avoids that kind of junk: Betty's party gown is "white", Lucy's is "sharp". In every scene he gives us what people are like, what they think, not what they "would" think. Mr Amos, a philosophical former slave who purchased his freedom, opines at one point, "A settlement seen from the sea is a very curious thing - who are these people who have come together to live in one place? And why?" Here are the genuine answers, colourful, arresting, fresh and enormous as any opera. Right here.

The Prisoner Of Paradise

Romesh Gunesekera

Bloomsbury, £16.99