In the Cut by Susanna Moore
Living alone in New York, Frannie teaches creative writing to a motley bunch of students, and secretly compiles a dictionary of street slang: virginia, n., vagina; snapper, n., vagina; brasole, n., vagina. One evening at a bar, she stumbles upon a man, his face in shadow, a tattoon on his wrist, a woman kneeling between his legs. A week later a detective shows up at her door.
The woman's body has been discovered in the park across the street. Soon Frannie is propelled into a sexual liaison that tests the limits of her safety and desires, as she begins a terrifying descent into the dark places that reside deep within her.