The best thing about this book is the picture on the back. A 15th-century portrayal of the victims of Fortune’s Wheel, its clear colours, graceful design and philosophical elegance offer a striking contrast to the novel’s drab writing, ungainly organisation and silly truisms. The Decameron model, with female characters sharing confessional stories, doesn’t work.

Their apparent variety is spurious; the same tired formulas are reapplied, the same uninspiring results recur. The novelist-narrator claims to hear other people’s thoughts, but they are barely worth recounting. Her linking narrative, telling of her anxiety about her marriage, the murder of a friend and the gradual collapse of services at the posh spa where the characters are staying, is numbingly banal. Elsewhere her manner is portentous, as she tells us, “the dead do come visiting”, or alleges that she has “served as a fulcrum for some balance between good and evil”. The gap between these pretensions and the perfunctory nature of the stories is embarrassingly wide.

Curiously, the group of “high achievers” hanging out in the Jacuzzi haven’t heard of each other, despite being the wives, ex-wives or lovers of a cabinet member, a “world-famous” cosmetic surgeon or a high-up in the BBC. One was a hostage in Iraq, another an Oscar nominee, but they still have to tell the others who they are. This isn’t, however, Boccaccio’s medieval era, but an age of instant global story-telling; the convention of naive autobiographical exposition is unconvincing.

Nor does it help that the stories display a lazy lack of invention. One tale concerns Shimmer and Sparkle, ferociously intelligent ex-Roedean sisters, who take up with two Geordie brothers. Dave and Pete – ho-hum – swear, belch, eat fish and chips and like rough sex. It’s hardly surprising that, despite all the gory details, the women are mere abstractions. In other stories, the “daring” plots involving sex changes, incest, abortions, murder of husbands, lesbian cyclists, child abuse and adulteries are unremarkable. The sex is unerotic, hampered by cliché.

There is little in Fay Weldon’s prose to detain the mind or intrigue the senses. Dialogue sometimes sounds like a poor translation (“Everyone drank, drugged and fornicated”). Leaden would-be aphorisms (“No good deed but goes unpunished”, “The dreariest suburb hides a free thinker or so”) need to shed some words. Trite observations from the gender wars include “men are different from women” and “we all turn into our own mothers”. These are not the narrator’s own, but they make her reflections on rage, jealousy, rejection and misery all the more shallow. The narrator tells us that, as a novelist, “it can be hard for me to tell the difference between the real and what I think is real”. Well, she inhabits an idiosyncratic world where nobody has heard of Gramsci, but there is a philosopher whose name is spelled “Kierkegarde”; where the TGWU can call a rail strike and the War of Jenkins’ Ear preceded the war of Spanish succession. “Men are terrified of brainy women,” says Sparkle. No, but they are bored by women who write trite complacent novels.

THE SPA DECAMERON by Fay Weldon
Quercus £14.99 pp336
Buy the book here at the offer price of £13.49 (inc p&p)

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy