All Her Fault Finale Explained: The Baby Switch, the Lie, and the Shocking Death

The final episode opens with Carrie—now revealed to be Josephine—pointing a gun at Marissa, Peter, and their family. Colin rushes her to try to grab the gun, but in the struggle she accidentally shoots him. She allows Lia to call an ambulance and run outside to let it in. She also allows Brian to go upstairs and attend to Milo, wo is now awake and calling out for his mom.

Carrie tells Marissa and Peter that she didn’t come to take Milo—she came to warn Marissa to protect Milo from Peter.

Marissa asks, “Protect him from what?” As Carrie begins explaining that Marissa doesn’t know what Peter did, Peter lunges at her again, forces the gun into her mouth, and shoots her. Marissa is horrified, realizing Peter didn’t want her to finish talking.

We flash back to the car accident six years ago. We learn that it was Marissa and Peter’s car that hit Josephine. Both couples were taking their newborn babies home from the hospital. After the crash, Peter tried to wake Marissa but couldn’t, and realized their baby had died. Then he heard crying coming from Josephine’s car. He went over, picked up her baby, and never put him down. He later admits to Marissa that he switched the babies, believing Josephine’s baby would have a better life with them since she was alone and they were a married couple. He insists he didn’t plan it—it happened in the moment.

When detectives interview Marissa and Peter, he tells them they had no idea Carrie Finch was actually Josephine Murphy. They tell them about the accident from six years ago, but say they never imagined it was connected to the kidnapping. Peter also explains that Marissa was in the hospital for weeks after the crash. When detectives ask Marissa why Josephine might’ve come to the house, she simply says she thinks Josephine was “crazy.”

Later, Marissa goes outside and listens to the recording Josephine had tried to play before she was shot. It reveals Peter at the motel, supposedly delivering ransom money—but instead, he killed Josephine’s father. Marissa confronts him, and Peter claims he thought it was all about money and knew it would never stop. That’s why he killed her father. He also admits that he hid Milo and put him in the trunk so he could stage Milo’s “return.” Marissa is horrified. Peter demands the phone with the recording, and she hands it over.

Marissa tries to return to normal life with Milo, but she is afraid of Peter and what he’s capable of. Lia visits to talk about Colin’s funeral arrangements including the food allergy information for the caterer. She admits she’s never really had to be an adult before. Marissa reassures her that it’s not her fault.

Peter wants Milo to go back to school—Milo wants to go too—but Marissa is scared to let him out of her sight. She invites Jenny over and tells her everything: the baby switch, Josephine, Peter’s lies. Jenny promises she won’t say anything and insists Milo is Marissa’s son, no matter what, and that Marissa can’t go to the police. Marissa admits she doesn’t know if she can stay married to Peter.

Meanwhile, Detective Alcaras takes his son for evaluations at his new school. They ask sensory-processing questions about colors, tastes, and how he perceives the world. Something clicks for Alcaras—Milo’s unusual sense of color, and something he read in Josephine’s old school files. He calls Josephine’s former guidance counselor, who explains that Josephine often said colors and tastes got mixed up in her mind. It seemed neurological, but her parents never had her evaluated. The detective explains what the condition is and notes that it’s genetic.

At Colin’s funeral, Brian tells Peter that he’s choosing to use his wheelchair and will move into assisted living. He says he forgives Peter, realizing he’d depended on him too much. Lia tells Peter that Colin’s sister sold his house, and the profits will cover the firm’s debts. Peter coldly responds that Lia never should’ve gotten involved with Colin—and that her relationship with him started all of this.

Later, Marissa kisses Peter, and he immediately begins to have an allergic reaction. She tells him she must have accidentally eaten soy. Peter reaches for his EpiPen, but it’s expired. Marissa screams for Lia to get the emergency kit from the car. Leah returns saying the kit isn’t there and the ambulance is eight minutes away. As Peter struggles to breathe and turns blue, he says to Marissa, “You always have an emergency kit.” She responds, “Yes—I manage your allergies.” Peter dies.

Detective Alcaras later talks to the first responder from the car crash six years ago. The responder confirms that when he arrived, only Peter and the baby were conscious, and he remembered it clearly because he’d never seen a baby die that young.

Lia is questioned next. Detectives ask whether she thinks Marissa truly read the labels or intentionally ate soy. We see a flashback of Lia watching Marissa at the funeral, paying close attention as Marissa checked ingredient labels. Leah tells detectives that she refuses to accuse Marissa—everyone can make a mistake. When detectives press her, asking if she wants to know the truth, Lia says no. She does not believe Marissa did it on purpose.

We then see Detective Alcaras at his son’s new school, where Sam is happy. The detective looks troubled, remembering what he did to get Sam into the school—and realizing he crossed ethical lines too.

He visits Marissa at her new home and explains synesthesia, an unusual neurological condition affecting how colors, tastes, sounds, and sensations are processed. It’s very rare and usually inherited. Josephine had it—meaning Milo inherited it too.

He tells Marissa he knows she was unconscious after the crash and that any decisions made were Peter’s, not hers. He says he isn’t following protocol by telling her this, but the case is closed. He admits he thought he would feel bad about how things ended, but he doesn’t—he feels fine with it. Then he leaves.

Marissa is shaken but relieved.

In the final scene, Marissa, Jenny, Milo, and Jacob are at Jenny’s house. The women sip wine while watching their children play. For the first time in a long time, everything feels peaceful and happy.

What did you think?

Change Image

• Loved it
• Hated it
• So/So