Dear Debbie (2026) is a psychological thriller by best-selling American author Freida McFadden. The novel follows housewife and advice columnist Debbie Mullen, whose cheerful “Dear Debbie” columns hide her dark side and her intelligence. As Debbie’s perfect life begins to fall apart, she seeks vengeance on those who have wronged her and is forced to confront her darkest secret. Major themes in the novel include The Danger of Secrecy in Relationships, Misogyny and Societal Control of Women’s Bodies, and The Lasting Effects of Traumatic Events.

This guide uses the 2026 Sourcebooks eBook edition.

Content Warning: The source text and this guide contain depictions of graphic violence, sexual assault, sexual harassment, substance dependency, and references to death by suicide and disordered eating.

Plot Summary

The novel is told alternatingly between the perspectives of advice columnist Debbie Mullen, her husband Cooper, and her friend Harley Sibbern. These chapters are punctuated by discarded drafts from Debbie’s advice column, in which she suggests that her readers take violent measures to solve common relationship problems.

Debbie Mullen struggles to navigate her relationships with her daughters, Lexi and Izzy. She hates Lexi’s boyfriend, Zane, and worries when Izzy is kicked off the soccer team. After an angry confrontation with a neighbor who blames her for cutting his electricity, Debbie makes breakfast for her husband Cooper, who is hoping to be made partner at his accounting firm.

Debbie is devastated when reporters from Home Gardening cancel a planned shoot in her garden in favor of her neighbor, Jo Dolan. Jo gleefully admits that she invited the reporters to her garden after seeing them at Debbie’s, believing her garden to be superior. Debbie buys beetle trap refills to sabotage Jo’s garden, then visits the gym, where she encounters her friend and trainer, Harley Sibbern. Debbie reminds Harley about their book club meeting, hiding the fact that she never enjoys the meetings. Debbie brings sandwiches with avocado to book club, despite knowing that Harley is allergic. The other club members eat the sandwiches and become violently ill. When Harley suggests food poisoning, Debbie seems confused.

Cooper’s boss, Ken Bryant, rejects his request for a promotion. When Cooper threatens to quit, Ken accepts his resignation. Debbie also loses her job at the Hingham Household when a letter writer takes Debbie’s advice and leaves her abusive husband, who then threatens to sue the newspaper. That night, Cooper and Debbie both lie to each other, pretending not to have lost their jobs. Cooper makes an excuse to leave the house, and it is revealed that Harley became friends with Debbie after beginning an affair with her husband, Cooper. Cooper returns home and admits to Debbie that he lost his job. Meanwhile, both daughters face their own challenges. Debbie learns that Coach Pike told Izzy to lose weight before kicking her off the team, and overhears Zane and Lexi fighting about a file on his phone.

It is revealed that Debbie has been growing opium flowers and other pharmaceutical plants in her garden. She drugs her husband and sneaks out to sabotage Jo Dolan’s garden with the beetle trap refills, then sneaks into Coach Pike’s home. Cooper wakes and panics over Debbie’s absence. He notes her location on Findly, the location-sharing app she wrote for their family, then passes out. The next morning, Debbie confronts Cooper’s boss in his home at gunpoint.

When footage appears on the Hingham Household website of Debbie’s married boss having sex with his secretary, he blames Debbie. Later that day, Coach Pike is arrested for filming his players in the locker room. Cooper returns to finish his last two weeks of work and learns that his boss, Ken, has apparently taken a last-minute fishing trip. Shortly after, a large sum of money is discovered missing from Cooper’s company’s accounts. Debbie has lunch at Harley’s house and discovers a man’s shirt. Harley secretly hopes she will recognize it as Cooper’s. That night, Harley is confronted by the sister of Edgar, her last married boyfriend, who tried to die by suicide after Harley convinced him to leave his wife.

Coach Pike is arrested when police find software connected to recently-installed cameras in the girls’ locker room on his phone. When Lexi breaks up with Zane, he threatens to share intimate photos of her with their school. Zane’s sexual exploitation of Lexi triggers memories of Debbie’s own experience being raped by a man named Hutch in college. She vows revenge and arranges to meet Zane in an abandoned park, where she drugs him and destroys the photos of Lexi. The next morning, Zane drunkenly crashes his car into the school. Debbie is confused when Lexi is upset by the accident.

Lexi and Izzy begin to suspect that their mother is responsible for Coach Pike’s firing and Zane’s accident, and they confront their father. Cooper searches Debbie’s Findly history and realizes that she was at Ken Bryant’s house the night before he left for his last-minute fishing trip. Cooper searches Ken’s house and finds him dead of a bullet wound to the head. When he finds his gun safe empty, Cooper worries that Debbie has stolen his gun to frame him for Ken’s murder. It is revealed that Cooper is secretly fighting an alcohol dependency, and that the woman he has been hiding calls from is his sponsor. Convinced Debbie has discovered his secret, he resolves to find her and save their marriage.

Harley arranges to ambush Debbie and Cooper by inviting them to dinner at the same time. Her plan is foiled when it is revealed that the man Harley knows as Cooper is actually Jesse Hutchinson, Cooper’s coworker and gym buddy. Debbie had discovered this fact when she discovered his shirt at Harley’s apartment. She recognized Jesse’s smell because he is Hutch, the man who raped her in college. Desperate for revenge, Debbie stole Jesse’s gun and used it to kill Ken Bryant and frame him for the murder. Debbie drugs Jesse, shoots Harley, and attempts to stage a death by suicide scene for Jesse. She is interrupted by Cooper and decides not to kill Jesse. Cooper admits his struggles with alcohol, and she reveals the truth of her rape. Debbie also reveals that she got rid of Cooper’s gun because she thinks guns are unsafe.

An Epilogue reveals that, one year later, Cooper has started his own accounting firm and Debbie has launched a successful app. They attend weekly couples’ counseling to work on honesty in their relationship, but Debbie keeps one last secret: Ken was the husband whose wife left him because of a Dear Debbie letter, resulting in Debbie’s firing. Debbie decided to kill Kevin to help Cindy, who had become her friend. In prison, Jesse is killed by other incarcerated men who learn about his history of sexual assault.