At one time or another, we have all surely harboured that Antiques Roadshow fantasy: the old painting gathering dust in the loft turns out to be a lost masterpiece worth millions. For Annie McDee, heroine of Hannah Rothschild's The Improbability of Love (Bloomsbury, £14.99), the chance acquisition of a centuries-old revered work of art is a mixed blessing.

When Annie purchases the small painting from a junk shop for her waste-of-space boyfriend, she is plunged into the art world - a place inhabited by high-camp dealers, greedy Russian oligarchs, snobbish society women, and other assorted, unsavoury characters. For Annie has bought The Improbability of Love, a lost work by Antoine Watteau, one of the most influential French painters of the 18th century.

We follow Annie's attempts to discover more about the painting as she simultaneously copes with the demands of her alcoholic mother, an unsatisfactory love life and a job which is not the dream one she had once envisaged.

This sounds gloomy, but it is far from that - if you did not know much about the passion and power behind the doors of the great auction houses and art dealers, you will by the end of this enchanting tale.

With occasional narration from the painting itself - and what an egotistical, witty masterpiece it is - the reader is given its provenance from creation by the impoverished Watteau through to its appearance in London at the auction event of the season.

'The painting has a secret past which some want to keep hidden forever'

Along the way, we meet its many owners, the kings, queens, mistresses and servants, who have passed or stolen the painting from one to another in acts of love or envy. But the lost masterpiece does not only inspire love, it seems to have the capacity to move its owners to great evil, too, as Annie finds out to her cost. The painting has a secret past, which some want to keep hidden forever, while others are intent on revealing the truth to the world.

Part well-crafted mystery, part thriller, part love story, Rothschild's The Improbability of Love takes its readers on a wonderful journey into a rarefied world usually only experienced by the wealthy few.

With exquisite timing, I read the book the same week that Picasso's The Women of Algiers became the most expensive painting to sell at auction, going for £102.6million at Christie's.

Rothschild's tale went some way to explain why, in the real world, certain works become such coveted items. Time I started clearing out my loft.