“You took my son,” Josie screams. In the chaos, Colin tries to seize the gun during a moment of distraction and is shot. Josie panics, insists she doesn’t want to hurt anyone, and allows them to call an ambulance. But it’s too late. Colin dies. From that moment on, Josie, too, becomes a murderer.

Milo calls out for his mother. Marissa tries to go to him, but Josie stops her. The mother is her. Or at least, that is how Josie sees it.

When Marissa asks who she really is and hears the name Josephine Murphy, she is stunned. “But you’re dead.” This is the true heart of All Her Fault — its central revelation. And ironically, it is not about individual blame. Not Marissa’s. Not Jenny’s. Not even Josie’s. But let’s get there.

Josephine says that if she simply tells the story, Marissa won’t believe her. She needs to hear it. Before she can play the recording, Peter grabs the gun. In the struggle, he kills Josephine. As always, he tries to rewrite reality: he claims the gun went off accidentally, that Marissa didn’t see it clearly. This time, it doesn’t work. Marissa already understands everything.

On the night they were driving home from the hospital with their newborn, there was a car accident. They collided with Josephine, who was also leaving the hospital with her baby. Marissa’s child died in the crash. Josephine did not. Peter switched the babies. His justification? He believed Josephine was dead. He “saved” Milo. He saved himself. And destroyed everyone else in the process.

Marissa cries not only because of the truth, but because Peter made her believe — for weeks — that the kidnapping was her fault. It never was. It was always his.

Before they can listen to the recording on Rob’s phone, the police arrive. Alcaras tries to impose order, initially treating the case as a family tragedy involving the Murphys. Peter tells his version of the car accident, insisting that he didn’t know Carrie/Josie was the woman they believed dead — and that she was obsessed with Milo, “thinking he was her son,” willing to kill everyone. Alcaras is unsettled: if Josie was so dangerous, why did she allow Lia to call an ambulance? Why let Brian take care of Milo? Something doesn’t add up. But Marissa confirms Peter’s story. Officially, the case moves on.

When Marissa finally listens to the recording Rob made before he died, she hears the full truth: Peter killed Rob not only to “save” Milo, but to eliminate the evidence of what he had done years earlier. Confronted, Peter still insists he did the right thing. Milo came home. And more than that — with Rob alive, they would never have been safe. He didn’t plan anything. He simply “reacted.” Productively.

Peter demands the phone back. Marissa hands it over. He doesn’t realize that, in that moment, she has already made a decision.

Day 10

Josephine’s autopsy report shows gunshot residue on her hand. Alcaras can’t prove that Peter killed her. The true motive is missing.

In the “normal” life after everything, Marissa lives in a state of constant tension. She and Lia are organizing Colin’s funeral. In the middle of logistical details, Marissa mentions that she hired a specific service “because of the allergy.” Whose allergy?

Peter informs her that the police have officially closed the case as self-defense. Everything is resolved. But there are still thirty minutes left in the episode.

Milo wants to return to school. Marissa appears worried about her child — but in truth, she is afraid of Peter being near him.

Jenny is at work when we see that Esther is now working as Jacob’s nanny. A disturbing detail. When Jenny receives a message from Marissa, she goes to see her and hears the entire truth. Marissa is trapped: if she turns Peter in, she loses Milo. Jenny stops her from going down that path. The secret will stay between them. The real question becomes: how does Marissa get away from Peter? Divorce won’t solve it. So what will?

On Day 22, Alcaras takes his son to the new school and has the final realization: synesthesia. A rare, hereditary neurological condition. Milo has it. With that, Alcaras understands everything. The truth is confirmed.

On the day of the funeral, near the sedatives, there is a box of poison. Marissa tells Peter she agrees with him. That they will move forward with their lives. While they receive guests to remember Colin, Peter eats from the buffet. He complains, once again, about not being able to “take care” of his siblings. With Brian, the manipulation no longer works. Still, he tries to gaslight Lia, blaming everything on her relationship with Colin.

The poison works silently.

Marissa appears to comfort Peter, reassuring him that their life is fine. Then he begins to feel ill. His throat starts to close. Marissa mentions that she didn’t check all the food because of his allergy. Peter tries to use his emergency injector. It’s expired. There isn’t another one in the car. He realizes it wasn’t an accident. The ambulance won’t arrive in time.

When Alcaras receives news of Peter’s death, he understands everything. He remembers the conversation on Day 27, when he and Greco spoke about death. It wasn’t about the kidnapping. It was about Peter.

Lia gives her statement, accompanied by a lawyer. Marissa claims she ate soy — the food Peter was allergic to — and then kissed her husband, accidentally triggering the fatal reaction. Lia immediately understands that it was intentional. And she chooses not to accuse Marissa. Because she remembers everything Peter did. How he made her carry guilt that was never hers. She supports her sister-in-law’s version and protects her from punishment.

Weeks later, Alcaras visits Marissa. He makes it clear that he knows the truth. That Peter was responsible for everything, long before Marissa understood what was happening — and that when she did understand, she had to make a choice. The case is closed. Marissa is not at risk. Still, he wanted to say one thing: “It’s okay.”

On a quiet afternoon, free of the husbands who blamed them for everything, Jenny and Marissa watch Jacob and Milo play together.

The cycle is complete.