On joining the editorial board of the nascent Virago in the 1970s and contemplating what kind of women's fiction Virago should publish, Angela Carter wrote to Lorna Sage: "I am moved ... by the desire that no daughter of mine should ever be in a position to be able to write By Grand Central Station I Sat Down and Wept." Carter's fear and loathing of the Jean Rhys/Elizabeth Smart/Edna O'Brien "suffering woman" was matched by a loathing of realism. She wanted to write fiction, she said, "without crap about the imitation of life getting in the way".

Carter's wildly imagined, highly stylised fantastical fiction managed to confound many a reader, not to say the literary establishment, who showered her with obituaries on her untimely death in 1992 yet never awarded her a major literary prize. She was not respectable, and she did not care, but she minded very much about reaching readers with "open minds who are not intimidated by the unorthodox".

Only death brought a measure of success. In that year Virago sold out of all her backlisted titles. She is now the subject of many a thesis, and Day's welcome, accessible study increases our understanding of Carter's statement: "You don't actually need a plot, or characters, only an idea, and a monomaniacal obsession with getting it across."

Because of her anti-realism and perhaps also because she invoked fairytales and folklore (if only to deconstruct them) the highly rational nature of her fiction often went unseen. She was frequently mistaken for a magical realist, but she was not interested in illusion, or in creating a world that made no distinction between fact and fiction. There was an assumption that she was embracing myth, yet she regarded myth as dangerously consolatory. Myth dealt in false universals employed to dull the pain of particular circumstances. "I'm a socialist, damn it! How can you expect me to be interested in fairies?" Symbols of the eternal feminine like the Mother Goddess and the passive, suffering, mad Ophelia (an image that haunts her fiction) were there to be reasoned out of existence.

ÖйúAƬ

Day is careful to distinguish Carter's idea of reason from Enlightenment notions. In The Sadeian Woman Carter's Marquis de Sade is "the last, bleak, disillusioned voice of the Enlightenment". Carter's reason is defined outside the binary antagonisms of masculine and feminine, reason and unreason, thought and feeling, a model in which relationships are based on the principle of reciprocity rather than self-definition by exclusion. As Fevvers says in Carter's last novel Nights at the Circus: "Life within those walls was governed by a sweet and loving reason. I never ... heard a cross word or a voice raised in anger."

Carter was an empiricist who used fantasy to investigate the material conditions of reality. Her fiction of ideas has a feminist political vocabulary that connects it to the real world. Day approaches Carter's fiction as allegory, and in a meticulous examination of the texts illuminates the way Carter's characters represent abstract concepts, as he teases out the argument inherent in the narrative.

ÖйúAƬ

Carter's work is inspired by her early desire to investigate what she called "the social fiction of my femininity". Her preoccupation with heterosexual identity is informed by a strong sense of history - what is determined can be reinvented; nothing, not even the flesh, is natural. She returns again and again to imagining futures free from the destructive weight of the past.

Day gives full credit to Carter's fierce intelligence, to her love of theory, and to her radical inventiveness. This engaging book goes a long way to setting the record straight.

Mary Tomlinson is fiction editor, Bloomsbury Publishing.