Victorian London is a place of fluid social roles, vibrant arts culture, fin-de-siecle wonders ... and dangerous underground diabolic cults. Fencer Evadne Gray cares for none of the former and knows nothing of the latter when she's sent to London to chaperone her younger sister, aspiring art critic Dorina. Unfortunately for Evadne, she soon learns too much about all of it when Dorina meets their uncle's friend, Lady Henrietta 'Henry' Wotton. A semi-respectable aristocrat in public, in private she is secretly in the thrall of a demon obsessed with beauty and pleasure. When Lady Henry and Dorina immediately hit it off, Evadne abandons her chaperone duties and enrolls in a fencing school. There, she meets the fencing master she's always dreamed of. But soon, George reveals he is more than just a teacher. He has dedicated himself to eradicating demons and their servants, and he needs Evadne's help. As Evadne gets pulled further into this hidden world, she begins to suspect that Lady Henry