Mackenzie is a 21-year-old college student who wears dark clothing, black lipstick, and heavy eyeliner. She lives in the shadow of her mother, the famous thriller author E.V. Renge, and experiences a confusing lack of traditional grief following her mother's sudden death. She secretly takes medication for an unnamed hereditary disease, choosing to hide her medical status from her parents out of resentment. When she begins receiving anonymous letters containing pages from her mother's diary, she becomes consumed by the investigation into her family's past.

Elizabeth publishes bestselling thriller novels under the pen name E.V. Renge. She spent her adolescence as a ward of the American foster care system, enduring trauma in a group home before securing a college scholarship. According to her private diaries, she uses writing as a therapeutic outlet to process her painful past, translating real violence into popular horror fiction. Her sudden death initiates the central mystery of the story.

Ben is Mackenzie's father and Elizabeth's widower. He comes from a wealthy background and relies heavily on his family's money and his physical charm rather than professional ambition. In the present, he spends his days drinking heavily to manage his withdrawal and visible anxiety. He acts paranoid around Elizabeth's locked office, searching through her cabinets with tools.

Tonya is a former resident of the Keller Foster Care group home where she lived alongside Elizabeth. She appears in Elizabeth's diaries as a vindictive figure who tracks Elizabeth down during college. She holds a severe grudge regarding a fatal barn fire that killed her boyfriend, Brandon. The diary entries describe her as a charismatic but obsessive individual who threatens to expose Elizabeth's secrets.

EJ is a 23-year-old computer programmer and Mackenzie's closest confidant. He earns a substantial income through online coding jobs, giving him the financial freedom to fund travel for their investigations. He acts as a steady emotional anchor for Mackenzie, researching police records and accompanying her as she works through her complicated feelings about her mother's death.

John is a popular social studies professor at Mackenzie's university who demonstrates deep respect for E.V. Renge's literary contributions. Prior to her death, he assigned his class a project analyzing the viral success of her novels. In the diary entries from the past, a man named John is described as a bartender and college peer who encouraged Elizabeth to submit her first writing to a competition.

Evelyn is Ben's mother and Mackenzie's wealthy grandmother. She exerts intense control over the Casper family, managing her son's alcohol intake and overseeing the financial estate. She actively curates the family's public image and uses non-disclosure agreements and trust funds to force compliance from her relatives.

Dianne is the retired housekeeper from Keller Foster Care, the group home where Elizabeth and Tonya spent their teenage years. She lives alone on a remote property behind a cattle gate. She clearly remembers the dynamics between the girls at the group home and the fatal barn fire that occurred during her tenure, providing Mackenzie with blunt answers.

Grunger works as the superintendent for the building where Elizabeth rents an apartment during her college years. He engages in illicit activities, including dealing drugs out of the property, and uses his access to the residents' apartments for his own opportunistic reasons.

Laima is the literary agent representing the highly profitable E.V. Renge brand. She is strictly concerned with the financial stability of the publishing contracts and views the author primarily as an intellectual property asset rather than a grieving family's loss.