Lenna is a 19th-century woman with a deep interest in biology and geology. Deeply skeptical of the supernatural, she temporarily suppresses her reliance on scientific evidence to apprentice under a famous medium. Her primary motivation involves uncovering the truth behind the recent death of her younger sister. She struggles to reconcile her rational worldview with the invisible world of spiritualism and her own private romantic desires.

Vaudeline is an internationally respected spiritualist medium who specializes in contacting victims of violent crimes. She left the London Séance Society under unexplained circumstances and now operates in Paris. She openly embraces her sexuality and maintains an unapologetic independence that defies Victorian gender norms.

Mr. Morely serves as the vice president of the Department of Spiritualism within the exclusive London Séance Society. He is a self-conscious man who experiences social isolation due to a large birthmark on his face. He seeks to maintain the Society's reputation following the murder of its president and the circulation of rumors regarding fraudulent mediums.

Evie is Lenna's deceased younger sister. Unlike her scientifically grounded sibling, she was a dedicated believer in spiritualism and an aspiring medium. She boldly sought access to the all-male London Séance Society by disguising herself in men's clothing. Her unexplained death drives the primary investigation of the story.

Mr. Volckman is the recently murdered president of the London Séance Society. Before his death, he oversaw the prestigious all-male collective and managed growing rumors of fraudulent mediums operating within its ranks. His unsolved murder prompts the Society to reach out to Vaudeline.

Constable Beck serves on the Metropolitan Police Force and holds membership in the London Séance Society. He provides security for Vaudeline and Lenna during their investigation in London. He acts as a bridge between formal law enforcement and the supernatural inquiries of the Society.

Mrs. Gray is a grieving widow for whom the London Séance Society recently performed a ceremony. She acts mistrustful toward the Society's male members but becomes receptive when Vaudeline demonstrates genuine mediumship skills.

Bennett works as a carriage driver for the London Séance Society. He is believed to be deaf by his employers, a trait that supposedly prevents him from overhearing sensitive conversations between Society members during transport.

Eloise is Lenna's former close friend and secret romantic interest. She died in a tragic accident alongside her father prior to the events of the novel. Her memory lingers over Lenna as a symbol of hidden desires and unresolved grief.

Mr. Heslop is Eloise's father and a former acquaintance of the Wickes family. He died under mysterious circumstances in an accident alongside his daughter.

Mrs. Cleland is Eloise's mother and the widow of Mr. Heslop. Following the accident that killed her husband and daughter, the Society performed a séance for her, after which she married one of the group's members.

Mr. Cleland is a member of the London Séance Society. He married the Heslop widow following the tragic accident that killed her first husband and daughter.

Mr. Dankworth is a medium working for the London Séance Society. He conducts séances for vulnerable widows and generates rumors regarding predatory behavior within the organization.

Stephen is a close family friend of the Wickes family and Eloise's brother. He courts Lenna, offering her advantageous professional connections to the world of geology and a socially acceptable future.

Mrs. Volckman is the widow of the murdered Society president. She experiences isolation in her grief, noting that the Society members have largely ignored her since her husband died.

Mel works as a sex worker at a brothel where the London Séance Society previously conducted an event. She provides Lenna with crucial details regarding the individuals who attended and operated the fraudulent séance.