Dr. John Cukrowicz, a surgeon at a New Orleans mental hospital, is tasked with evaluating a young woman named Catherine Holly, who has been institutionalized after a traumatic event the previous summer. She is haunted by the mysterious and violent death of her cousin, Sebastian Venable, while on vacation in Spain. Dr. Cukrowicz is intrigued by Catherine's condition and her cryptic statements about Sebastian, despite her fragile mental state and allegations of insanity. Meanwhile, Catherine's wealthy and dominating aunt, Violet Venable, offers to fund the hospital in exchange for the doctor performing a lobotomy on Catherine to silence her disturbing memories.

Violet insists Catherine is insane and claims that the surgery is necessary for her well-being. However, as Dr. Cukrowicz delves deeper into the case, he becomes suspicious of Violet's motives and the legitimacy of her version of events. During his investigations, he conducts interviews and attempts to piece together the truth about what really happened that fateful summer. As he gets closer to unlocking Catherine's repressed memories, Dr. Cukrowicz must navigate the manipulative influences of Violet and protect Catherine from those who wish to suppress the truth at any cost. At the core of the mystery lies a confrontation with socially taboo topics and dark family secrets that challenge accepted norms and question moral boundaries.