The Colour by Rose Tremain

A gold-rush is a wonderful subject for a novel. Gold is the stuff of our dreams. Men desire it because it is transformative. Karl Marx loved Timon of Athens, of all Shakespeare's plays, for depicting gold as the whore-of-change, turning one thing into another, rendering this man servile, that man vain.

A gold-rush is a wonderful subject for a novel. Gold is the stuff of our dreams. Men desire it because it is transformative. Karl Marx loved Timon of Athens, of all Shakespeare's plays, for depicting gold as the whore-of-change, turning one thing into another, rendering this man servile, that man vain.

Like her own characters, Rose Tremain is for ever re-inventing herself: as a girl turning herself into a boy (Sacred Country); as courtier to a Renaissance Danish King (Music and Silence); as an adolescent boy in contemporary Paris (the marvellously touching and funny The Way I Found Her). Now, in The Colour, she evokes New Zealand's South Island during the 1860s, when saloons and grog-shops, gambling dens and dance halls, sprang up to attract the gold of the "New Iniquity".

A walk-on character graphically says that women will wash their hair in the piss of a man newly enriched for "one ounce of what he's got". A once respectable landlady puts on rouge and keeps a rowdy house. A Chinese fisherman becomes an enterprising nursery gardener. A married man hunting for gold ("the colour") turns in his loneliness to a charming, wild rent boy for consolation. Tremain is always interesting about male homosexual behaviour.

So this is an adventure story, full of the detail of colonial settlement, the paraphernalia of gold-quest, of natural wonders like a flash flood, and of memorable animals. Yet, like many good novels, the main concerns are spiritual. For all its vividly researched backdrop, this is essentially a book about egotism, discontent and our longing for the marvellous. It shows how happiness and misery change into their opposites; how both imagination and love – notably, happy sexual love – alter what they touch as much as gold ever can.

Harriet Blackstone is an engaging heroine. Resourceful, tough, wise, she wants to go beyond the bounds of the known, and has the brave curiosity and simple luck to encounter much that she seeks. Joseph – her limited, selfish husband – is son to a Norfolk livestock auctioneer who died bizarrely. He emigrated after marriage to escape responsibility for a crime and, when his farm fails, seeks gold. Those with gold fever must be secretive, lest others discover and exhaust what they hope to plunder. But Joseph, in not trusting his own wife, fails to measure what she is made of, and ceases to deserve his good luck in finding her.

One pleasure in reading Tremain is her freedom from know-all pessimism: the least of her characters is pleasure-loving, with a feeling for the poetry of things. Even Joseph's crotchety mother wonders how the socially privileged effortlessly make us feel their superiority – "like a perfectly executed card-trick". Those she favours have generous imaginings or daring visions. She lends them her tender, quizzical sensibility, a romantic (in the best sense) feeling for seeing the world anew.

Tremain is prodigal, inviting us into the shape-shifting world of a prescient Maori servant-girl. She loves a courageous English child who also welcomes what is different and surprising. Dying, he longs to reveal to his prosperous mother that "there was no end to what was possible in the world".

Henry James mocked traditional novel-endings that distributed "prizes, pensions, husbands, wives, babies, millions, appended paragraphs and cheerful remarks". Tremain's endings are neither cheerful nor conventional, but rather abound, like good tragedy, in an extraordinary admixture of grief and joy. This novel is no exception. It is a fabulous work, bravely imaginative, deeply moving, surprising, invigorating and satisfying.

Peter J Conradi's life of Iris Murdoch is published by HarperCollins