The Satisfying Ending of ‘All Her Fault’ Works on Two Levels

If you haven’t yet watched Peacock’s All Her Fault, I cannot recommend it enough. It’s one of the year’s strongest streaming series, topping the ratings the week it premiered and anchored by terrific performances from Sarah Snook and Jake Lacy. But what makes its ending especially satisfying is that it works on two distinct levels: the mystery it resolves and the deeper story it reveals about control, truth, and the legacy of someone who insists on shaping other people’s lives.

Here’s how the story unfolds.

Marissa Irvine (Snook), a successful wealth manager and mother of a five-year-old boy named Milo, arrives at a stranger’s home to pick him up from a playdate. The woman at the door has never heard of Milo. Within minutes, Marissa realizes that her son has been abducted.

She and her husband, Peter (Lacy), mobilize immediately, joined by Peter’s siblings Lia (Abby Elliott) and Brian (Daniel Monks), and Marissa’s friend and coworker Colin Dobbs (Jay Ellis). Detective Alcaras (Michael Peña) leads the investigation as the public turns on Marissa, blaming her for trusting the wrong person or accusing her of staging the kidnapping for attention.

The kidnapper is eventually identified as Carrie Finch, nanny to Marissa’s new friend Jenny Kaminsky (Dakota Fanning). But her motives don’t fit any of the obvious theories. She wasn’t having an affair with Peter. She wasn’t being extorted. It wasn’t a ransom plot. And Jenny herself wasn’t involved. The mystery isn’t who took Milo — it’s why.

At the same time, the cracks in Peter’s carefully maintained facade shatter. What begins as the portrait of a supportive husband shifts into something darker. Long-buried family secrets emerge, including how Peter caused the accident that disabled his brother as a child but allowed his sister to believe she was responsible, feeding her guilt and addiction. Over the years, Peter constructed a family dynamic in which everyone — his siblings, his wife — depended on him completely.

This is the show’s second level: a portrait of a man who defines reality for everyone around him and will do anything to protect the version of that reality he prefers.

Three-quarters into the series, Milo is suddenly returned to a police station. But the mystery remains unsolved. When Carrie returns to the Irvines’ home with a gun, Colin attempts to disarm her and is killed in the struggle. Carrie wasn’t there to reclaim Milo — she came to deliver the truth. She carries an audio recording explaining everything.

Before she can play it, Peter shoots her. It is not an act of self-defense. It’s an act of control.

Marissa manages to grab Carrie’s phone and hears the recording. It reframes the entire story.

Here’s what really happened: Six years earlier, Marissa and Peter left the hospital with their newborn, while Carrie left with hers. A car accident left both women unconscious. Marissa’s baby died. Carrie’s survived. Terrified of losing the family he imagined — and unwilling to let Marissa experience that grief — Peter swapped the infants. Marissa unknowingly raised Carrie’s son, while Carrie spent years mourning the loss of hers.

This is level one of the ending: the twist that resolves the mystery.

But what makes the ending work so well is how seamlessly it delivers level two: the thematic truth the show has been building toward. Peter has spent his entire life rewriting reality to preserve control — from his siblings’ guilt to Marissa’s marriage to the very identity of their child. When the truth finally surfaces, it doesn’t just expose the kidnapping; it exposes Peter.

Once Marissa understands what Peter has done, she realizes that going to the police would mean losing Milo, who would likely end up in foster care since Carrie is dead. And before Carrie died, she asked Marissa to protect him. Marissa chooses the child she raised — the one she loves — even if he’s not biologically hers.

She intentionally eats soy, knowing Peter is violently allergic, then kisses him, triggering a fatal reaction after she removes the EPIPENs from the house. Peter dies. Detective Alcaras eventually deduces what happened, but understanding the moral terrain Marissa faced, he closes the case quietly.

The ending lands because it completes both layers of the story. It resolves the plot — who took Milo and why — but it also reinforces the show’s deeper themes: that truth can be stolen, rewritten, and weaponized, and that reclaiming it often comes at a cost. Marissa’s final act is not just about justice but about breaking free of a man who believed he had the right to define her life, her family, and her reality.