All Her Fault ending explained: Who was Carrie and why did she take Milo?

*Warning: This article contains full spoilers for the final episode of All Her Fault.*

The eight episodes of All Her Fault quickly unravel the mystery of Milo’s (Duke McCloud) disappearance, revealing the identity of his captor along the way.

Jenny’s new nanny, Carrie Finch (Sophia Lillis), seemed particularly interested in Milo. She gained the trust of Milo’s parents, Marissa (Sarah Snook) and Peter (Jake Lacy), by becoming friendly with their other nanny, Ana (Kartiah Vergara), and then took Milo.

Everyone was puzzled about why she’d taken Milo, especially since she wasn’t demanding any money. Luckily, the latest episode focused on the happy reunion of Marissa, Peter, and Milo. But the relief didn’t last – Carrie unexpectedly showed up at their house with a gun, demanding to have her son back.

What led to the events in the last episode of All Her Fault, and why did Carrie end up taking care of Milo? Keep reading to discover the full story.

All Her Fault ending explained: Who was Carrie and why did she take Milo?

Carrie keeps everyone at gunpoint, but she’s briefly thrown off when she hears Milo calling for his mom on the living room nanny cam. She insists she would never harm Milo, and Colin seizes the opportunity to intervene, attempting to disarm her. A struggle ensues, and Carrie accidentally shoots Colin in the stomach.

Carrie insists she didn’t intend to cause harm and asks someone to call for an ambulance. Peter encourages a distraught Lia (Abby Elliott) to go outside and wait for paramedics. Brian (Daniel Monks) tries to comfort Milo, but after he leaves, Peter quietly acknowledges that Colin has died.

Marissa finally asks Carrie the question everyone’s been wondering: who is she, and why did she take Milo?

Carrie reveals her true name is Josephine Murphy, and Marissa instantly recognizes her, shocked to hear she’s still alive. Carrie admits she often wishes she were, but feels like she lost herself six years ago. She desperately asks Marissa, as one mother to another, to protect their son, Milo, from Peter.

Honestly, it was a tense moment. Carrie was desperately trying to warn Marissa about Peter, saying there was a side to him Marissa just didn’t know. She started explaining something that happened years ago – something before the ambulances even arrived – a secret Peter had apparently kept hidden. Carrie was fumbling for her phone, trying to play a recording to prove her point, when Peter just…lunged at her. It happened so fast, it was scary!

He shoots a frightened Carrie, killing her instantly. Peter quickly tries to explain it as an accident to Marissa, claiming the gun fired on its own. However, Marissa realizes Peter intentionally killed Carrie to prevent her from exposing a secret.

Marissa demands Peter tell her exactly what happened the night of the car accident. They were driving home from the hospital with their newborn son, Milo, when another car hit them. Peter was the only one who was awake during the crash, and he turned around to find Milo had died and Marissa seemed unharmed. We then see a flashback to Marissa’s shoulder scar, revealing it was caused by the devastating collision.

Currently, Peter confesses to Marissa that their son actually died in the car accident. However, we see a flashback to that night where, after calling 911, Peter hears a baby crying. He finds a newborn baby boy in the other wrecked car and holds him, as sirens approach. He admits to Marissa that he didn’t intend to, but he switched the babies, believing Carrie had died in her vehicle.

He believed she wasn’t capable of providing Milo with a good life, especially since she was on her own. He felt she wasn’t fit to be a mother and that he had prevented a future filled with hardship for everyone involved. He warned Marissa to keep everything secret, fearing Milo could be taken from them if the truth came out.

Police confirmed the two additional bodies they discovered were those of Carrie’s boyfriend and father. Peter explained his confusion regarding Carrie and Josephine, and why he didn’t immediately recognize her photo. However, Detective Alcaras suspected something wasn’t right, particularly because Carrie let Lia call for an ambulance and allowed Brian to help Milo.

Marissa secretly listened to a recording on Carrie’s phone and discovered a shocking truth: Peter visited Carrie’s father at a motel. Carrie’s father revealed that Carrie suspected the car accident wasn’t accidental and that Milo actually belonged to him. Peter arrived with ransom money, but instead of paying Carrie’s father, he attacked him with a lamp. As Carrie’s father lay dying, Peter declared he’d saved Milo and that Milo was his son.

Peter admitted he was the one who picked up Milo, but he’d covered Milo’s eyes and left him at the police station to avoid being connected to the motel.

I believe that in the midst of the shock and confusion, believing Milo’s birth mother was dead and his newborn son had also passed away, he convinced himself he was saving his wife from unbearable grief – that he was keeping their family together. That’s the story he tells himself, and if an actor can focus on that – on this seemingly selfless act – it makes sense, even though it’s clearly wrong to take such control. It’s not his decision to make, Peter.

What happens to Peter?

Now that things are getting back to normal, it’s obvious Marissa doesn’t fully trust Peter, especially when it comes to their son, Milo – Peter seems to have a need for control. She reaches out to Jenny, needing to talk, and explains everything that’s been happening with Peter. Marissa admits she’s afraid of Peter and worried about the potential consequences if she decides to leave him.

While at the doctor with his son, Detective Alcaras discovers synaesthesia, a condition where senses can become mixed up. This reminds him of Milo, and he contacts one of Carrie’s old teachers, who confirms his hunch that Carrie may have had the same condition.

At Colin’s funeral, Peter and Brian had a strained conversation when Brian announced he was moving and starting a new job. Brian also argued with Lia, and Marissa later discovered him in Colin’s basement. They shared a kiss, but Peter quickly began choking, showing signs of an allergic reaction.

Oh my gosh, it was so scary! He was trying to grab his EpiPen from his jacket, but when he checked, it was actually expired! Marissa, who handles his meds, was super confident she hadn’t mixed anything up. She told Lia to call 911 and get the emergency kit from the car, but when Lia got back, it wasn’t there! The ambulance was going to take eight minutes to arrive, and nobody in the crowd around us had another EpiPen. It was a really tense situation.

As Peter struggles for air, he realizes Marissa knew this would happen – she confirms she planned to kill him, and he remembers she always keeps an emergency kit in the car. We then see a flashback to earlier that day, where Marissa deliberately took the kit out of the car and replaced it with a broken pen, ensuring Peter wouldn’t survive. Shortly after, Detective Alcaras receives the devastating news that Peter has died.

People often react strongly to the idea of a character’s journey ending, but a good story needs resolution. It’s satisfying for both the audience and the actor – getting to play out a dramatic death scene is always a fun challenge. That’s really why I’ve always loved acting, ever since I was a child – it’s the joy of pretending and exploring all sorts of incredible scenarios.

What happens to Marissa?

The next day, police questioned Lia, and it came out that Marissa must have eaten something containing soy – the allergen Peter was severely allergic to. Lia explained she was careful to label everything, and the police asked if Marissa had checked the labels or if she’d simply overlooked them.

It turns out Marissa did read the labels, and Lia witnessed her doing it. However, when questioned by the police, Lia recalled Peter’s harsh words to her at the wake and decided to lie to protect Marissa.

When we see Marissa again, she’s at home with Milo, preparing to move. Detective Alcaras arrives and tells her about the shared condition, synaesthesia, that both Milo and Carrie experienced. He explains that he knows Marissa was unconscious and unaware of Peter’s actions, and that he believes Peter was responsible for the death of Carrie’s father and for putting Milo in the car’s trunk. He understands that Marissa only learned about these events when Carrie showed up at her door, forcing her to deal with a very difficult situation.

Despite solving the case, he informs Marissa that it’s now officially considered closed. Though he knows something feels off, he says he’s okay and walks away.

Marissa and Milo excitedly ran down the road to visit Jenny and her son, where they spent a pleasant evening together, laughing, talking, and enjoying wine.

All Her Fault lands on Sky and NOW as a boxset in the UK on Friday 7th November.

Don’t miss “Add All Her Fault”! Watch it on the TopMob: What to Watch app. Download the app now for daily TV suggestions, exclusive features, and more.

2025-11-07 18:39

All Her Fault ending explained: Who was Carrie and why did she take Milo?

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