The Verdict
This is All Her Fault, book versus show, and it spoils the endings of both. If you haven’t finished either, pause here.
So, which is better, the book or the show? Here is my short answer. The big twist is the same in both. The setting, the police, the marriages and the deaths are all different. The book is Irish, short chaptered and mean. The show, reportedly, is American and bigger, with more room for its detective.
The book has four narrators, seven days, and a final page that makes you shiver. The show has a lot of talent and a lot of reasons to depart from it. Both are gripping.
A note on sources: I’ve read the novel in full. The series facts come from published reporting, as of October twenty twenty six, and I’ll say when something is reported.
The Author
First, a word about the writer. Andrea Mara lives in Dublin with her husband and three children, and her author note says she is an Irish Times Top Ten bestselling author who has been shortlisted for Irish Crime Novel of the Year. Before thrillers, she ran a parenting and lifestyle blog called OfficeMum dot ie.
In her acknowledgements she jokes about her career pivot from financial services to fictional murdering. That is no accident. Her school gate scenes feel lived in, from the playdate texts to the nanny politics.
All Her Fault was first published in twenty twenty one by Bantam Press, and it was her first thriller published in the UK and internationally. Five years on, it has a screen adaptation.
The Series
The adaptation is an eight episode limited series on Peacock, reported to have premiered in November twenty twenty five. Megan Gallagher is the creator, and the cast includes Sarah Snook as Marissa, Dakota Fanning as Jenny, and Sophia Lillis as Carrie. Michael Peña plays a detective.
Reports say it follows the novel’s spine. A child vanishes from a school pick up, the nanny is blamed, and a husband hides a terrible secret about the boy. But almost everything around that spine has been rebuilt.
Dublin To Chicago
The most obvious change is the setting. The book takes place in Kerryglen, a wealthy Dublin suburb, where the Irvines live at Maple Lodge. The show moves everything to a Chicago suburb.
The fake playdate address changes too. In the book, Marissa goes to fourteen Tudor Grove, and in the show, reports say, it is fourteen Arthur Avenue. Jenny Kennedy becomes Jenny Kaminski.
You also lose the Irishness. The book has gardaí, Dun Laoghaire pier, a witness at the Killiney Hill Obelisk and a nation on edge. The show swaps all of that for an American search.
The Irish Map
It is worth seeing how Irish the book is. Milo is found asleep in a car in Sandymount, and the red brick bungalow where he was kept is in Sandymount too. His raincoat is left on Killiney Hill, under the Obelisk. The investigation is run from Blackrock Garda station.
Peter and Carrie meet at a playground in Dun Laoghaire, near the pier. Carrie’s invented childhood home sits on the road between Bray and Enniskerry in Wicklow, and her real father is moving to Schull, in West Cork. Kyle Byrde did time in the Joy, which is Mountjoy prison. The Irvines escape to an apartment in Marbella, in Spain. And in the last chapters, Marissa and Jenny walk the East Pier at Dun Laoghaire, looking out at the bay, and Marissa cannot tell Jenny what she knows.
All of that is local colour a Chicago version has to replace. You can’t swap the Obelisk for a different monument without changing the mood.
The Marriages
Jenny’s story changes a lot. In the book, Jenny and her husband Richie are drifting. She suspects he resents her promotion, and he suspects her colleague Mark. His mother Adeline stirs, and anonymous notes arrive.
The show reportedly drops Mark and Adeline altogether. Instead, Richie tries to balance his job with hers and be a good dad, and the couple promise to work harder on both.
Marissa’s marriage is the opposite. In both versions, Peter is the villain, and one report says the show makes him more openly villainous. The book hides it longer.
The Police
In the book, Detective Sergeant McConville is a calm woman who rarely gives an inch, and, as one reviewer puts it, the police largely stay at the edges of the story. The author even thanked her garda advisers for never giving her fictional officers a day off.
The show gives its detective much more room. Reports describe him as a major character, with a family storyline of his own. That is a TV choice. Over eight episodes you need a person to follow outside the two mothers.
The Smaller Roles
The book has a bigger supporting cast than you might expect. Irene, Carrie’s mother, narrates her own chapters. She sells her story to a tabloid, is refused payment, and goes on television anyway, then moves to Bristol with her husband. She is selfish, funny and sad all at once.
Reports say the show gives Irene a smaller part, and spends the time on others instead. Peter’s brother Brian, his sister Lia and the business partner Colin are described as being built out more on screen.
In the book, Brian’s mystery turns out to be an affair with a woman who works at an estate agents. Lia is a brash sister home from New York. Both are more atmosphere than plot, which is probably why TV wanted to grow them.
Who Dies, And How
Now the part that matters. In the book, the same people die in a different order and manner. Carrie is smothered in bed by Peter. Rob Murphy shoots Colin, and then Peter shoots Rob.
In the show, reports say Peter shoots Carrie instead. And Colin dies when Carrie accidentally shoots him, not at Rob’s hands.
Peter’s fate is the biggest swerve. In the book, he dies in Marbella from shellfish, and the novel never says outright what Marissa did. In the show, reporting says Peter dies from a soy allergy after Marissa kisses him at Colin’s funeral, and he realises she meant it.
The Shared Twist
Let me spell out the twist both versions share, because it explains why every other change is allowed. Four years before the story, Marissa and Peter were in a car crash on an icy morning, just after their son was born. Peter found his baby dead. He also found the other driver’s baby alive.
He put his dead son into the other car seat and carried the living child out. Paramedics assumed that baby was his. The other driver, a young woman called Carrie, was told her baby had died.
Years later Carrie sees Peter in a playground. Milo is describing colours to him, and Carrie sees the same synaesthesia and the same smile. That’s how she knows. That’s why the title is so cruel.
What Stays The Same
The heart of it is untouched. In both, the boy Milo turns out to be Carrie’s biological son. After a car crash, Peter swapped two babies, and Carrie was told her child had died. In the book she spends months planning to get him back.
In both, Peter kills to keep it hidden. And in both, a mother in a lovely house discovers she has been married to a monster. That is the line that carries the title.
What Only The Book Has
Some pleasures only the book can give. There is the way each chapter is stamped with a day count, such as Monday, three days missing, which makes the clock feel physical. There are the invented news site comments, with strangers deciding that the Irvines staged it for money.
There is the school gate gang called the Coven, whose casual cruelty about foreign nannies is one of the book’s quieter villains. And there is the last page, where Adeline types a new anonymous note in capital letters and thinks that her son will never know it was her.
The book also ends on the newspaper report from Marbella, cold and flat, with Marissa saying only that Milo is safe at home with his nanny. It is a chilling last line. I love that it makes the reader decide.
Why Change Anything
So why do adaptations change so much? A novel can run on four voices and seventy nine tiny chapters. A series needs a single character to anchor eight hours, and it needs set pieces. A shooting in an industrial estate is more cinematic than a pillow in a bungalow.
I think the changes make sense on those terms. What I’m less sure about is the shift of blame. The book’s Peter is a slow poison. His crime isn’t the killing, it’s the first lie on the icy road. If the show makes him louder, that’s a different kind of story.
The title also lands differently. In the book, it describes the whole city blaming Jenny and Marissa and Carrie, the women. Peter’s the one nobody looks at.
Which First
So, which should you pick? I think you should read the book first, because the twist is built from small clues. A nickname, a rented house, a page behind a printer, a little boy who sees days in colour. They land best on the page. Then watch the show for the bigger cast, and to see how it changes the deaths. If you do it the other way round, you’ll already know the shape of the twist, and you’ll miss the small pleasure of spotting the clues. That’s my opinion, and yours may differ.
If you’ve watched the show, which death change did you prefer? Tell me in the comments. For the full ending of the novel, watch my ending explained video, and the plot walk through is on the All Her Fault page at bookexplained dot com. Subscribe if you like these, and thanks for watching.
