1901. Denton, a writer with a reputation for involving himself in murder cases, is used to getting unconventional mail. But one particular letter gets his attention: a note from a young woman, Mary, saying she's in terrible danger and needs his help. The letter is months old, and was only forwarded to him when the buyer of a painting found it stuck behind the frame. Presumably whatever Mary was frightened of has already happened. So why did she hide the note behind this particular painting, instead of sending it? The search for answers leads Denton into the heart of Bohemian London - the world of artists and their models, a world of brilliance and depravity, of unconventional morals and shifting sexual identities, where the border between genius and madness is hard to discern but easy to cross. And before he has learned the shocking truth, Denton will discover what it's like to be the object of a lethal obsession and endure a terrifying confrontation with his own demons.