Comparing “All Her Fault”: Key Differences Between the Show and the Book
Peacock’s All Her Fault presents an intriguing, fast-paced mystery series — but how does the television adaptation stack up against the original novel?
Inspired by a book by Andrea Mara, All Her Fault centers on Marissa (Sarah Snook), a mother whose son, Milo, goes missing during his first playdate. The quest to find Marissa’s child reveals hidden secrets among her close acquaintances, turning everyone into a potential suspect in the kidnapping.
The series debuted in November 2025, captivating viewers with the twist that not every scene on screen matched what was written in the book. Stars Abby Elliott and Daniel Monks shared with Us Weekly how changes were made to fit the show’s narrative.
“When I started reading the novel, I found that Brian seemed quite different from what Megan had initially penned,” remarked Monks, who portrays Brian. “Therefore, I thought, ‘I should focus on the scripts for now and set the book aside.’”
Elliott had a similar journey with her character Lia, stating to Us, “My discussions with Megan at the beginning were crucial. She advised me to wait on reading the book so I wouldn’t have it clouding my interpretation.”
She added: “Lia entered the story much later, and as a New Yorker, she embodies a different vibe. By the time I joined, Megan had already given these characters so much depth that they felt radically distinct from the book.”
Continue reading to discover the key differences between the show and Mara’s original narrative:
Expanding on Peter’s Family
As previously mentioned, the adaptation took liberties in developing Brian and Lia. Lia’s character was mostly absent since she was situated in New York while the Irvines resided in Dublin (later changed to Chicago in the series).
The show delved into Lia’s struggles with past substance abuse and depicted her secret relationship with Marissa’s business partner, Colin (Jay Ellis), prior to his (spoiler alert!) untimely death.
In contrast, Brian lived with Peter (Jake Lacy) in both the book and the series, albeit for different underlying reasons. The show revealed that Brian, injured in childhood, suffers from a disability, adding another layer of mystery.
Marissa and Jenny’s Friendship
Given that their relationship is a key element of the story, Marissa confided in Jenny (Dakota Fanning) about her intention to eliminate Peter, a plot point that did not occur in the book.
Adaptations like Little Fires Everywhere, Big Little Lies, and You highlight how many best-selling novels have transitioned to the screen. Reese Witherspoon plays a significant role in several successful adaptations, fueled by her enthusiasm for bringing captivating stories to audiences.
Jenny’s Personal Life
As for Jenny, while relationship struggles were present in the book, they stemmed from conflicts with her mother-in-law. The show portrayed her estrangement with her husband more definitively, suggesting a more permanent divide.
The Major Deaths
The most significant discrepancies are found in the circumstances surrounding the deaths — with Rob murdering Kyle and Peter killing Carrie (in the series, smothering with a pillow versus a shooting in the book). The details of Peter’s death were also altered, switching from a shellfish allergy to a soy allergy.
Carrie’s Backstory
The adaptation devoted less time to exploring Carrie’s (Sophia Lillis) mother, whereas the novel presented her as using her daughter’s legal difficulties for personal gain.
More Time With the Detective
Peacock’s limited series introduced a notable personal link for Detective Alcaras (Michael Peña) to the case, enhancing the brief appearances this character had in Mara’s novel.
