Shea is a 29-year-old receptionist and true crime blogger living in Claire Lake, Oregon. After narrowly escaping an abduction at age nine, she lives by a strict set of personal rules to maintain her safety, such as refusing to ride in cars or meet men alone. She runs a website called "The Book of Cold Cases," where she researches unsolved crimes.

Beth is a wealthy, reclusive woman who lives alone in her family's sprawling Claire Lake mansion. In 1977, she was tried and acquitted for a series of crimes known as the Lady Killer murders. Because of her affluent background and reserved demeanor, the public widely assumes she is guilty. She eventually agrees to let Shea interview her, opening up about her childhood and the tragic deaths of her parents.

Lily is a girl who enters Beth's life during childhood, initially introduced to the household under vague circumstances. She returns to the Greer mansion every Christmas. Lily exerts a strong, often intimidating influence over Beth, encouraging her to stand up to bullies while demonstrating a surprisingly cruel streak.

Michael is a private detective and former Claire Lake police officer. He frequently assists Shea with her true crime blog research. He respects Shea's boundaries, working with her for over a year without pushing to meet her in person.

Joshua is a retired police detective living on a houseboat in Claire Lake. During his career, he handled high-profile investigations, including the Lady Killer murders and a highly publicized child abduction case. He maintains a complicated view of Beth Greer's guilt and encourages Shea's writing.

Esther is Shea's older sister. She lives a conventional life with her husband and wants to see Shea break out of her self-imposed isolation. Despite their differences and occasional distance, she cares deeply for Shea's emotional well-being.

Julian is Beth's wealthy father. He purchased the Greer mansion in 1950, creating a bizarre mix of architectural styles to appease his wife. He maintains strict control over the family finances and meets a violent end in the home's kitchen.

Mariana is Beth's mother, a woman who struggles with her mental health and her unhappy marriage to Julian. She relies heavily on her husband for financial support and carries a difficult history that predates her marriage.

Ransom is the longtime legal counsel for the Greer family. He represents Beth during her 1977 murder trial. He harbors personal feelings for Mariana and works aggressively to protect the family's interests from the press and police.

Melvin is a state police detective assigned to assist with the Lady Killer investigation. He is aggressive in his questioning and firmly believes Beth is guilty of the murders.

Anton is the man who attempted to abduct Shea when she was nine years old. After she escaped his car, he abducted and murdered another young girl, leading to his eventual imprisonment.

Sherry is a young girl who was abducted and murdered by Anton Anders shortly after Shea's escape. Her death heavily impacts Shea, who carries lasting survivor's guilt over the tragedy.

Sylvia is Julian Greer's former secretary. She provides Shea with historical details about Mariana Greer's mental health and the family's secretive financial arrangements.

Winston Purrchill is a cat adopted by Shea. Taking him in represents a small step in Shea's process of opening her isolated life to outside connections.