What happened to Carrie and Milo? Peacock show All Her Fault’s chilling finale twist explained
Set against the heartbreaking backdrop of a mother's relentless efforts to locate her kidnapped son, All He Fault's ending was the most unexpected one. Based on the book of the same name by Andrea Mara, the mystery thriller follows Marissa Irvine (Sarah Snook), who, along with Jenny Kaminski (Dakota Fanning), unravels the shocking truth behind Milo Irvine's (Duke McCloud) disappearance, giving fans a taste of one of the best mystery thrillers of recent times.
Notably, in the show Milo returns, but his unexpected return leaves Marissa rattled, especially with police still unable to find Carrie Finch (Sophia Lillis), who has already killed two men. Her situation worsens when she discovers her close friend Colin Dobbs (Jay Ellis) has been stealing from their firm to cover gambling debts and that his bookie is one of Carrie's victims. Suspecting Colin's involvement in Milo's abduction, Marissa and her husband confront him at home, but in the middle of a heated family argument, Carrie suddenly walks in, that too armed, as per People. Notably, in the second-to-last episode of 'All Her Fault,' Carrie's growing fixation on Milo is revealed, along with how she kidnapped him with help from her felon boyfriend, Kyle, and her bookie father, Rob.
Though portrayed as mentally unstable after losing her own baby at 16, the final episode exposes the deeper twist that Carrie, whose real name is Josephine Murphy, believes Milo is actually her biological son. After accidentally killing Colin in a struggle, Carrie insists she never meant to hurt anyone and only came to warn Marissa about Peter Irvine (Jake Lacy). The series then reveals a shocking twist that six years earlier, Carrie, Marissa, and Peter were in a car crash that killed a newborn. Marissa believed Carrie died by suicide afterward, but Carrie claims she survived, and that it was actually Marissa's baby who died that night.
According to her, Peter, the only conscious adult after the crash, switched the infants, passing off Carrie's child as Marissa's. Before she can prove it, Peter shoots and kills her, later claiming it was self-defense despite her begging for her life. In the finale, it's confirmed that Carrie is Milo's biological mother. Before police arrive, Peter admits to Marissa that he switched the babies after the crash, believing Carrie had died. Detective Alcaras (Michael Peña) reaches the same conclusion when he notices both Carrie and Milo share synesthesia. Although he suspects Peter murdered Carrie, there isn't enough evidence to charge him. As for Peter, Marissa discovers he also killed her father to keep Milo's true identity hidden, but he convinces her not to go to the police, fearing she could lose Milo.
Weeks later, Peter has a fatal allergic reaction to soy during Colin's funeral. His EpiPen is expired, the backup kit is missing, and as he dies, he realizes Marissa intentionally poisoned him. In the end, as Peter is dying, the show flashes back to reveal that Marissa set up his death by removing their emergency allergy kit and swapping his working EpiPen with an expired one. In the final scene, Detective Alcaras tells her he knows what Peter did and is okay with not pursuing the investigation. The series ends with Marissa peacefully watching her son play, sharing wine and relief with Jenny, and finally feeling safe.