Affinity is a tale of power and possession that Henry James himself might admire. In her first novel, Tipping the Velvet, Sarah Waters explored secrets and longing--capping off this lesbian romp with a utopian-socialist vision. Her intricate follow-up is just as sensual but infinitely darker, its moral more difficult to descry. Its stylistic and psychological rewards, however, are visible at every turn, the author's persuasive imagination matched by her gift for storytelling.

In late September 1874, Margaret Prior makes her way through the pentagons of London's Millbank Prison, a place of fearful symmetry and endless corridors. This plain woman on the verge of 30 has come to comfort those behind bars, several of whom Waters brings to instant, sad life. And our lady visitor plans to take her role seriously, having recovered from two years of nervous indolence in her family's Chelsea house. One person, however, makes her job a passion. Opening an inspection slit (or "eye" as these devices are known), Margaret hears "a perfectsigh, like a sigh in a story". Peering inward, she's confronted by the most erotic of visions--a woman turned towards the sun, caressing her cheek with a forbidden violet: "As I watched her, she put the flower to her lips, and breathed upon it, and the purple of the petals gave a quiver and seemed to glow..."

The medium Selina Dawes may indeed have the face of a Crivelli angel, but she is in prison for fraud and assault. Suffice to say that the first full encounter between these two very different women is enthralling. "You think spiritualism a kind of fancy," Selina riddles. "Doesn't it seem to you, now that you are here, that anything might be real, since Millbank is?" And soon enough Margaret receives several viable signs of the supernatural: a locket disappears from her room, flowers mysteriously appear and her dazzling friend knows everything about her. Strangest of all, Selina seems to love her.