The Breakdown (2017) is a psychological thriller and B. A. Paris’s follow-up to her internationally bestselling debut, Behind Closed Doors. The Breakdown was a Goodreads Choice Award Nominee for Best Mystery and Thriller in 2017. It has been adapted into a film titled Blackwater Lane, released in 2024 and starring Minka Kelly, Maggie Grace, and Dermot Mulroney. The novel portrays Cass Anderson’s battle with guilt and fear after a woman is murdered near her home and Cass comes to believe she’s the killer’s next target. Her husband and her best friend dismiss her fears because Cass has been disturbingly forgetful lately, and everyone, including Cass, wonders if she’s losing her mind. The Breakdown explores the impact of guilt and fear on mental health and the erosion of trust and honesty in relationships in an illuminating depiction of psychological abuse.

This guide uses the e-book edition of the text published in 2017 by St. Martin’s Press. Pagination may differ from print editions.

Content Warning: The novel and guide describe psychological distress, attempted death by suicide, murder, and trauma.

Plot Summary

The Breakdown begins with protagonist Cass Anderson attending a party with her fellow teachers to celebrate the end of the school year. Before heading home, she calls her husband, Matthew, who’s in bed with a migraine. He makes her promise not to take Blackwater Lane, an isolated shortcut through the woods, but a severe storm leads her to break her promise. Seeing a car pulled over on the side of the lane, she pulls over, but though the woman in the car is looking at Cass, she does nothing to indicate that she needs help, so Cass drives on.

The next day, Cass learns from the news that the woman she saw was murdered shortly after. She’s overcome with guilt, especially after learning the victim was Jane Walters, a woman she’d recently befriended. Adding to her distress, Cass has started to experience small memory lapses. She’s terrified she’ll be diagnosed with dementia, the disease that shattered her mother’s final years. Small lapses become larger: Her best friend, Rachel, is annoyed when Cass forgets her agreement to purchase a gift for a mutual friend; Cass signs a contract to have an alarm system installed but doesn’t remember having done so. She then begins receiving repeated calls from someone who remains silent when she answers.

Cass comes to suspect that Jane’s killer saw her on Blackwater Lane and considers her a threat. The calls, she concludes, are the killer’s way of warning her not to go to the police. However, her shame about not helping Jane led her to keep the encounter a secret, so now she can’t justify her theory to Matthew or Rachel. Worried by Cass’s memory lapses and her seemingly groundless claims that a killer is targeting her, Matthew convinces her to see a doctor. At first, she’s reluctant to take the pills the doctor prescribes, but when she thinks she sees the murder weapon in her kitchen and has a meltdown, she relents. The pills are a sedative, and soon Cass sleeps through most of every day.

Matthew becomes increasingly frustrated with Cass’s memory lapses, paranoia, and emotional outbursts. When she insists that someone has been in their house and Matthew doesn’t believe her, a big fight ensues. Cass wakes up the next morning feeling extremely ill. At the hospital, tests reveal a high level of the sedative in her bloodstream. The doctors believe she attempted death by suicide. Horrified at what her life has become, Cass decides to take back control. She visits Jane’s husband and confesses that she saw Jane on the road shortly before her murder. He assures her that she’s not to blame and even persuades her that the harassing phone calls she has been receiving likely aren’t from the murderer.

Soon after this, Cass goes out to dinner with Rachel, who departs unexpectedly early. A girl at another table then hands Cass a phone, saying her friend took it from Rachel’s purse on a dare. It looks like a burner phone and has only one saved number. Cass calls the number but hangs up, shocked, when Matthew answers. She learns more from the text thread on the phone between Matthew and Rachel. It reveals that the two of them are having an affair and have been scheming to make Cass think she’s losing her memory and her mind. She collects evidence of their schemes and then seeks revenge by calling the police and implicating Matthew and Rachel in Jane’s murder.

Cass is shocked when her tips help the police discover that Rachel was Jane’s killer. In her confession, Rachel reveals that Jane knew about the affair and threatened to tell Cass. Rachel and Matthew intended to get Cass certified as mentally unstable so that they could get her inheritance money, which Rachel felt entitled to because of her close relationship with Cass’s parents. Learning the truth and bringing Jane’s killer to justice sets Cass free from her guilt and fear, and she knows she’ll eventually be okay again.