Unlike most muses, Francie Thorn is supremely lovable. A casual, unselfconscious eccentric, she swishes through life: 'Why burn the leaves,' she thinks idly in autumn, 'what good would it do? Why shave your legs or wash a dish?' She has two daughters; rather than bringing them up, she observes their growing up. And she observes herself with the same unjudging eye. Alighting dispassionately on the effects of passion, when she first meets her lover, Sam, she notes: 'Although I continued to face Helle, it was as if my own womb had inside it a tiny compass, its needle indicating correct orientation: the pole's tug was to my left, where Sam now stood.'
In this generation of women writers, love is often shortchanged. Few can counterbalance their intellectual weight with dreams, or their romantic tics with realism. But Davis writes of a love between equals that still has tragic modulations. This is the real thing, caught in a language that hovers enticingly between the laconic and the poetic.
Francie Thorn's heterosexuality is at odds with her other lover's lesbianism, and her American nonchalance is set in contrast with the weight of Helle's European past. Helle's Europe is mythical in an unexpected way - no gay Paree or sunny Rome, but the dark northern temper of Hans Christian Andersen, Coppelia and 12th-century castles. While Francie's America is brittle and bright, a country of azure diners and dusty pink birthday cakes. But despite the outright difference of their backgrounds, we come to believe that as women Francie and Helle come from the same world.
The book's strange title is the name of an Andersen fable in which a young rich girl treads on a loaf of bread to save her shoes from being spoilt by ooze in a bog, and then descends to the realm of the Bog Queen. That realm - marshy, dark, all- female - is Helle's natural habitat, and in her opera of the fable the bog takes over the stage. Dark, damp, underground images also come to dominate Francie's life. We hear a great deal about the drops of water that cling to the undersides of leaves, the dampness of the bedding in cheap lodgings, sheets of drizzle and curtains of mist.
That metaphorical density implies the depth of this female love. Given that the novel opens after Helle's death, with Francie looking back over her life and work, it amounts to an emotional haunting. Even though, as we finally learn, Helle has destroyed Francie's only real chance of happiness, that hardly affects their unique sisterhood, which always forced Sam to take a peripheral role: 'In fact, the image I was coming back to over and over again - Francie Thorn wading among dark wet rocks, plucking from nests of seaweed the iridescent mussels she would later coax open over a fire, revealing to her two little girls the secret of the meat hidden within each shell . . . didn't include Sam at all.'
These neat triangles and heavily symbolic images work because Davis has learnt to use metaphor in an attractive Nabokovian way, both flamboyantly upfront and much too mysteriously personal to be ironed out by the eye of the critic. The treatment of Helle's musical oeuvre proves this sophistication. Partly a source of feminist allegories, it is also a cornucopia of random and unexpected imaginative riches; when Helle writes an opera of Woolf's The Waves we hear that she creates parodies of six musical styles for the six separate voices, a Debussyish style for Bernard, Bach for Susan, Mozart for Rhoda's tuneful style: 'I hear a sound, cheep, chirp, cheep, chirp, going up and down.' Although the opera is unimaginable, it is a fine, intelligent conceit.
So Davis gains our emotional and intellectual trust. And when the novel's denouement arrives, with its shots in the night and unexpected deaths in a sudden, symbolic downpour, we can appreciate the moment in many ways - as plot, like the mad devastations at the ends of operas that leave one cathartically satisfied; as allegory, balancing out the triangle we always knew was highly symbolic; and as real life, in which we weep for Francie.
The thick layers of this novel only become transparent once you have reached the end and tripped over the tragedy. But re-read it, and you are struck by the piquant harmonies all the parts make. For once, this is a novel with secrets, one that repays work, and its prose is exquisitely rhythmic and open-ended. Take the resonant last sentence, after Francie finally frees herself of the dragging weight of both Helle and Sam, and meets a naughty little girl who is teasing a small boy. 'Really, I said, sibylline, magnificent in my red winter coat, you should be nicer to him, or else.'