Peacock’s ‘All Her Fault’ Unveils Key Differences from the Book

Peacock’s new mystery series, All Her Fault, premiered in November 2025 and has quickly captured viewers’ attention. Adapted from the novel by Andrea Mara, the show focuses on Marissa, played by Sarah Snook, whose son, Milo, mysteriously disappears during a playdate. As she searches for her child, Marissa uncovers unsettling secrets about those around her, with each character becoming a potential suspect.

The adaptation diverges significantly from the source material, and stars Abby Elliott and Daniel Monks recently shared insights about these changes. Monks, who portrays Brian, noted that his character seemed “unrecognizable” compared to the book. He stated, “I think that needs to wait for later so I can focus on the scripts.” Similarly, Elliott, who plays Lia, was advised by Mara not to read the book initially to avoid preconceived notions about her character.

Character Development and Changes

The show takes a new approach to character arcs, particularly with Lia and Brian. In the book, Lia is largely absent, as she resides in New York while Marissa’s family is in Dublin, a location that was changed to Chicago for the television adaptation. The series delves deeper into Lia’s backstory, exploring her struggles with substance abuse and her secret relationship with Marissa’s business partner, Colin, portrayed by Jay Ellis. This relationship adds layers to the plot, especially following Colin’s shocking death.

Brian’s character also receives significant development. While he resides in Peter’s house in both versions, the show reveals that he is disabled due to a childhood accident. This detail not only adds depth to his character but also introduces another layer of mystery throughout the series.

Plot Differences and Key Events

The dynamics of Marissa and her friend Jenny, played by Dakota Fanning, differ notably between the two formats. In the series, Marissa confides in Jenny about a drastic plan to remove Peter from their lives, a plot point not present in the book.

Jenny’s personal life is also adapted. While the novel hints at her marital struggles due to a difficult mother-in-law, the series portrays her split from her husband as more definitive, altering the emotional landscape of her character.

Perhaps the most striking differences involve pivotal deaths in the narrative. In the book, the circumstances surrounding the deaths of Rob and Peter differ significantly from the show. For instance, Peter’s method of killing Carrie shifts from a shooting in the book to smothering her with a pillow in the series. Additionally, the reasons behind Peter’s demise change from an allergic reaction to shellfish to a soy allergy in the adaptation.

The show also places less emphasis on Carrie’s mother, who in the book manipulates her daughter’s legal troubles for personal gain. Additionally, Detective Alcaras, played by Michael Peña, sees an expansion of his role, with the series providing more background on his personal connection to the case, enhancing the narrative depth.

As fans continue to engage with Peacock’s All Her Fault, the differences between the series and the book underscore the creative liberties taken in adapting literature for the screen. The changes not only redefine character relationships but also reshape the unfolding mystery, making it a unique viewing experience that diverges from its original storyline.