Mackenzie calls her mother’s therapist to ask about Elizabeth’s mental health, but he refuses to disclose any information. Then, she receives a call from a company called Huckleberry Supplies about a bill that is two months overdue, but she ignores it. Moments later, she receives a text instructing her to check her mailbox for a new letter from E. V. Renge’s number-one fan.

When Elizabeth confronted Tonya about her affair with Ben, Tonya explained that Brandon, one of the three boys who assaulted Elizabeth and whom Elizabeth later killed, was her first love and that she was seeking revenge for his death. Heartbroken about the affair, Elizabeth sought comfort from her friend John, who worked in a local coffee shop.

Mackenzie realizes that her mother’s book The Wolf Whistle is likely based on her college experience with Tonya and Ben. She calls EJ to discuss the letter and is disappointed when he is too sick to see her. When she arrives at her university, she is annoyed to find that it is hosting a celebration of life for her mother and renaming a lecture hall after her.

EJ secures a copy of the police report about the barn fire, which reveals that it was likely arson and that the three boys were drugged. Tonya was questioned about the fire because of her relationship with Brandon, but she had a solid alibi. Elizabeth was not questioned. Now confident that her mother caused the fire, she wonders if she also killed Tonya, who disappeared after their college years.

Heartbroken by Ben’s betrayal, Elizabeth began a new novel based on her experiences in which she enacts gruesome revenge on a character based on Tonya. She also threatened to break up with Ben, which made him want her even more. Although initially disturbed by the novel, Ben recognized her genius and apologized for the affair. Elizabeth then revealed that she was pregnant.

Letters begin appearing at Mackenzie’s college apartment, and although she knows that this means the deliverer is likely stalking her, she doesn’t care. She becomes obsessed with reading and rereading the letters and her mother’s novels for new details about her life. She starts to write letters to her mother, though she knows she can’t respond.

Elizabeth’s pregnancy was hard, especially after a series of strange events, including finding a dead rat in her apartment. Her memory began to falter, and she would find her closet rearranged or new furniture in the apartment. Ben ended his affair with Tonya, who seemed to disappear entirely. Elizabeth’s friendship with John faltered after he learned that she planned to stay with Ben.

Although devastated by her mother’s pain in pregnancy, Mackenzie finds a strange sort of comfort in the letters. She begins to remember moments when her mother was kind and gentle toward her, like when she got her first boyfriend. Another time, her mother suggested that they were more alike in talent and beauty than she had previously admitted.

After Ben and Elizabeth graduated, Ben began traveling to see his parents once a month, claiming that his mother was sick. When Ben’s mother, Evelyn, called to tell Elizabeth about a recent trip to Greece, Elizabeth realized that Ben had been lying to her. Ben confronted Elizabeth about the barn fire, and she realized that he had resumed his affair with Tonya.

Mackenzie questions whether her mother may have had a mental illness such as borderline personality disorder. EJ suggests that maybe the letters are fiction, like her novels. Mackenzie decides that she needs to visit her mother’s foster home and the town where her parents met. EJ agrees to accompany her on the condition that she let him pay for the trip.

EJ attempts to find records for people who lived in the foster home with Elizabeth but is unable to find anything substantial. He finds records for a housekeeper who was questioned several times about the house fire, and Mackenzie notes that a housekeeper character features prominently in Elizabeth’s book about her assault. They decide to contact her on their trip.

Mackenzie tones down her typical goth makeup look for the trip to Nebraska, not wanting to scare any of the people they are going to see. She and EJ plan to visit Elizabeth’s old foster home and then see the home’s retired housekeeper two hours away before returning to the city for one night. When they stop at a gas station on the way to the airport, Mackenzie finds another letter.

Two weeks before Mackenzie was born, Ben and John got into a violent fight that ended with Ben stabbing John with a broken bottle. Elizabeth decided that she did not want a husband like Ben, and the letter implies that she wanted to be with John instead. Elizabeth believed that for her to be happy, either Ben or Tonya had to disappear.

Mackenzie and EJ realize that the seventh letter is written in the present tense, rather than the past tense, meaning that Elizabeth wrote the letters while she was pregnant with Mackenzie. Mackenzie’s excitement about the trip turns to dread as she realizes that she will be forced to confront the places and people that hurt her mother so deeply.

On arrival in Nebraska, EJ and Mackenzie drive to Keller Foster Care, which has been closed for 15 years. A chain-link fence has been erected around the building, and the word “hell” is spray-painted on the door. Broken windows suggest that rocks have been thrown at it. Mackenzie takes a quick picture but rejects EJ’s suggestion that they explore.

As they drive to the former housekeeper’s home, the empty, eerie landscape of Nebraska disturbs Mackenzie. EJ attempts to encourage her, and she begins to feel something for him beyond friendship. When they arrive at the address that EJ found online, they push past a cattle gate and onto the property. Confident that the house is occupied, EJ attempts to push inside but stops at the sound of a gun cocking.

The former housekeeper, Dianne Jacobson, immediately recognizes Mackenzie as Elizabeth’s daughter and agrees to talk to them. She says that Elizabeth was a quiet, shy girl who was always different from the other students at the home. She is unsurprised when Mackenzie says that Elizabeth was a world-famous writer and does not react when she learns that she has died.

Dianne confirms that Elizabeth was assaulted in 10th grade and that a board investigation decided not to charge the boys responsible after Tonya testified that Elizabeth was lying. Mackenzie suggests that Tonya was obsessed with one of the boys who assaulted Elizabeth, but Dianne claims that Tonya was obsessed with Elizabeth.

When Mackenzie brings up the barn fire, Dianne suggests that the boys who died had wronged many people and that she suspects it was a prank gone wrong. She says that Elizabeth sent her Christmas cards for a few years after graduation and then became withdrawn. She confirms that Tonya was pregnant when she graduated and gave up the baby in an anonymous adoption.

Before leaving Dianne’s house, Mackenzie offers her a copy of Lies, Lies, and Revenge, the novel based on Elizabeth’s experiences at the foster home. When Dianne reacts oddly to the author photo, Mackenzie shows her more photos of her mother, including one of her when Mackenzie was one year old. Shocked, Dianne claims that the woman in the photo is not Elizabeth but Tonya.