The Stepmother's Diary is Fay Weldon's 28th work of fiction. In some ways, it shows. There are signs of haste: why is a wedding in a register office apparently using the Church of England marriage service? Why do Weldon's narrators so often reach for clichés (or get them wrong: surely the literary-critic husband would know that the past is a “foreign country” in LPHartley's famous opening to his novel The Go-Between, not “another country”)?

But with that sort of form also comes reliability. Weldon, professor of creative writing at Brunel University, knows what she is doing. And what she is doing in The Stepmother's Diary is taking a classic situation familiar from Snow White or Rebecca (the new wife who takes the place of the sainted dead one) and seeing how it looks now.

Sappho is married to Gavin, who has two children by his previous marriage to the doomed genius Isolde. We are introduced to this unhappy foursome just as it is about to split apart. Weldon adds an extra dimension with another narrative voice, Sappho's psychoanalyst mother, Emily, who starts reading the sheaf of papers her daughter dumps on her after turning up on her doorstep in distress. This diary and Emily's reactions to it make up the novel.

Emily's responses to her daughter's unravelling of the story of her marriage are coolly professional at first, focusing on Sappho's “psychosexual development” and masochistic urges. But as the complications and downright lies of the past are revealed, the psychoanalyst gives way to the mother. At the last, Emily metamorphoses - Barnaby, her Jungian friend, helpfully points out - into “vengeful” Hecate, “lying upon the floor, possessed, kicking [her] feet into the carpet”.

Barnaby tells Emily that her Freudian interpretations of Sappho's life are old hat. But Weldon has deliberately constructed a family dynamic that reads like a Freudian case study, with primal scenes of children walking in on significant adults having sex, or long-buried secrets about fathers and mothers suddenly resurfacing.

In truth, much of the novel seems schematic, with Weldon carefully putting the pieces into place. The ones that don't fit make it worth reading. There is Emily's tumbledown house in north London, taken on by Sappho, which gradually becomes a succubus, draining the life from all who come near it, and occasioning an almost prophetic outburst from Emily: “I invoke a curse on all who love their houses more than themselves...I curse and condemn the mad usurious system which invented mortgages the better to control us, to render us passive and powerless, dangling on the rope of interest.” There are also shafts of acute social observation, as of teenage girls' habit of “always hugging each other, and laughing and weeping on each others' shoulders. One never knows whether they are being sincere or satirical or posing for the media”.

It is a shame that this intelligent if sometimes workmanlike novel has been packaged as the flimsiest sort of chick-lit: the faux-sexy cover does Weldon a grave disservice. In a way, it subverts much of what her fiction exemplifies: that what women do, and think, and write about, is serious stuff, which can't be prettified, pigeonholed, or tidied away.

The Stepmother's Diary by Fay Weldon
Quercus £16.99 pp265

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