Under the plain gray skirts of Miss Beatrice Lockwood's gown, a pistol waits at the ready. For Beatrice is a paid companion on a secret mission—and with a secret past—and she must be prepared to fight for her life at any moment.

Yet she is thrown oddly off guard by the fierce-looking man who joins her in foiling a crime outside a fancy ball—and then disappears into the shadows, leaving only his card. His name is Joshua Gage, and he claims to know Beatrice's employers. Beyond that, he is an enigma with a hypnotically calm voice and an ebony-and-steel cane.

Joshua, who carries out clandestine investigations for the Crown, is equally intrigued. He has a personal interest in Miss Lockwood, a suspected thief and murderer, not to mention a fraudster who claims to have psychical powers. The quest to discover her whereabouts has pulled him away from his mournful impulses to hurl himself into the sea—and engaged his curiosity about the real Beatrice Lockwood, whose spirit, he suspects, is not as delicate as her face and figure.

He does know one thing, though: This flame-haired beauty was present the night Roland Fleming died at the Academy of the Occult. Guilty or not, she is his guide to a trail of blood and blackmail, mesmerism and madness—a path that will lead both of them into the clutches of a killer who calls himself the Bone Man.