Peacock’s All Her Fault is a mysterious and fast-paced mystery series — but how does the TV adaptation compare to the original book?
Based on a novel by Andrea Mara, All Her Fault follows a mother named Marissa (Sarah Snook) whose son, Milo, disappears from his first playdate. The search for Marissa’s child uncovers secrets about those closest to her, with everyone becoming a suspect in the kidnapping.
The series, which premiered in November 2025, captured our attention — as did the revelation that not all events on screen occurred on the page. Stars Abby Elliott and Daniel Monks spoke exclusively to Us Weekly about making changes for the sake of the show.
“For me with the novel, I started reading, and their Brian seemed unrecognizable from the one that Megan had written,” Monks, who plays Brian, noted. “So, I was like, ‘I think that needs to wait for later so I can focus on the scripts.’”
Elliott had a similar experience as Lia, sharing with Us, “With Lia, it was the same kind of thing when I talked to Megan at the beginning of the whole process. She explained the story and she said, ‘Don’t read the book until after because you don’t want that in your head.’”
She continued: “Lia came in much, much later, and she’s a New Yorker. So it’s a very different vibe, and Megan had fleshed out these characters so much already that they were completely different than the book.”
Keep scrolling for the main differences that took place on the show compared to Mara’s version:
Expanding on Peter’s Family
As mentioned above, the show developed Brian and Lia in a way that varied from what is in the book. Lia was largely out of the picture, because she was in New York while the Irvines were in Dublin (which was changed to Chicago on the show).
Peacock’s version explored Lia following a past substance abuse issue. She was also in a secret relationship with Marissa’s business partner, Colin (Jay Ellis), before his (spoiler alert!) death.
Brian, meanwhile, lived in Peter’s (Jake Lacy) home in the book and the show — but for different reasons. The show revealed that Brian was disabled following an accident when the siblings were young, which is another mystery on screen.
Marissa and Jenny’s Friendship
With their bond being so central to the story, Marissa told Jenny (Dakota Fanning) her plan to get rid of Peter, which didn’t happen in the book.
Jenny’s Personal Life
Speaking of Jenny, the book version also featured issues in her marriage, but they were the result of a difficult mother-in-law. Jenny appeared to potentially reconcile with her estranged husband while the show made their split more permanent.
The Major Deaths
The biggest difference is the circumstances surrounding the deaths — including Rob murdering Kyle and how Peter killed Carrie (smothering with a pillow vs. a shooting). Details around Peter’s death were swapped from a shellfish to a soy allergy.
Carrie’s Backstory
The show didn’t invest as much time in Carrie’s (Sophia Lillis) mother, while in the book she used her daughter’s legal troubles to her advantage.
More Time With the Detective
Detective Alcaras’ (Michael Peña) personal connection to the case was introduced to Us in Peacock’s limited series, which expanded on limited screen time in Mara’s novel.
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