Violet is an aging, wealthy widow who presides over a palatial estate in New Orleans's Garden District. Devoted entirely to the memory of her recently deceased son, Sebastian, she aggressively protects his reputation as a chaste, brilliant poet. She tightly controls her family's finances and uses her wealth to manipulate relatives and medical professionals alike.

Catharine is Violet's niece, currently confined to St. Mary's mental institution where she undergoes intense shock therapies. She spent the previous summer traveling abroad with her cousin Sebastian before his sudden death in the Spanish town of Cabeza de Lobo. Facing severe opposition from her family, she refuses to retract her account of the trip despite the looming threat of a lobotomy.

Dr. Cukrowicz is a young, financially struggling surgeon who works at Lion's View Hospital. Specializing in experimental lobotomies, he evaluates Catharine's mental health at Violet's request. He maintains an observant, polite demeanor while weighing his medical responsibilities against the lucrative financial grants Violet offers his hospital.

Sebastian is Violet's recently deceased, forty-year-old son. A fastidious aesthete and aspiring poet, he spent most of his life traveling to glamorous locations with his mother, producing exactly one poem each summer. His sudden, violent death in Spain serves as the central mystery dividing the Venable and Holly families.

Mrs. Holly is Catharine's mother and Violet's sister-in-law. She is highly motivated by the inheritance Sebastian left her and her son, which Violet currently blocks in probate. She prioritizes securing her financial future over her daughter's psychological wellbeing.

George is Catharine's tall, handsome younger brother. Ambitious and heavily focused on social status, he eagerly anticipates receiving the $50,000 left to him in Sebastian's will. He treats his sister cruelly, demanding she silence herself so the family can access the money Violet holds back.

Sister Felicity is a strict, starched-habit-wearing nun from St. Mary's mental hospital. She acts as Catharine's chaperone and enforces the institution's restrictive rules, stripping Catharine of small comforts like cigarettes.

Miss Foxhill is Violet Venable's secretary and personal assistant. She attends to Violet's practical needs around the estate, pushing her wheelchair and organizing the extensive paperwork related to Sebastian's death.