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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsSpoilers for the entire first season. Milo is Carrie Finch’s biological son. Carrie’s birth name is Josephine (“Josie”), and she lost him five years before the series begins. After a crash killed Peter and Marissa Irvine’s baby, Peter secretly switched that dead infant with Josie’s living newborn. When Carrie later recognized Milo’s synesthesia—the ability to “taste” colors, which she shares—she became convinced that the child she had lost was alive and abducted him. Milo is eventually recovered and returned to Marissa, but Peter’s lie destroys nearly everyone involved.
Why did Carrie take Milo?
Carrie first encounters Milo while accompanying her father, Rob, on an errand linked to Colin Dobbs’s debt. Milo tells her that he can taste colors. Carrie has the same form of synesthesia, and the coincidence convinces her that Milo is the baby she lost.
That belief explains Carrie’s motive, but it does not make the abduction lawful. Milo is living with Marissa and Peter as their son, and Carrie takes him rather than using the discovery to seek help or establish the truth. The series therefore presents her as both a grieving mother with a real biological connection and a kidnapper whose decision puts a child and other people in danger.
Who is Milo’s biological mother?
Carrie Finch is Milo’s biological mother. Her original name is Josephine, or Josie. The child Marissa gave birth to died in the crash five years earlier; Josie’s newborn survived.
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The secret baby exchange
Peter was the only adult conscious after the crash. Knowing that his and Marissa’s baby was dead, he exchanged the bodies and concealed the surviving baby’s identity from Marissa. Marissa consequently raised Josie’s son without knowing it, while Josie believed her own child had died.
Peter’s deception is the story’s causal hinge. Carrie’s later kidnapping, the attempts to expose the truth, and the killings in the finale all grow out of his decision to preserve the false family history.
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How the finale unfolds
Carrie confronts the Irvines
Carrie arrives at the Irvine home armed. During a struggle over the gun, she accidentally shoots Colin. She begins telling Marissa that Peter has hidden the truth about the babies, but Peter attacks before Carrie can fully explain.
Peter kills Carrie
Peter fatally shoots Carrie and then presents her to police as a jealous kidnapper. His final act is another attempt to control the story: he removes the person who can expose the swap and frames the crisis as a nanny’s obsession rather than the consequence of his own lie.
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At Colin’s memorial, Marissa deliberately triggers Peter’s soy allergy by eating soy. His expired EpiPen fails, and the backup injector is unavailable because Marissa did not pack it. Detective Alcaras understands what she has done but does not pursue legal punishment.
That ending is not presented as a clean legal resolution. Creator Megan Gallagher describes Marissa and Alcaras as confronting the difference between law and justice: both recognize that a morally satisfying outcome and a lawful one may not be the same thing. The show leaves viewers to judge whether Marissa’s revenge is justice, murder, or both in different senses.
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Who is responsible for the deaths?
| Person | Action | Outcome |
|---|---|---|
| Peter Irvine | Swaps the babies after the crash, later kills Rob, and shoots Carrie. | Dies after Marissa triggers his soy allergy. |
| Carrie/Josie | Abducts Milo and accidentally shoots Colin during the confrontation. | Is fatally shot by Peter. |
| Rob | Murderously pursues the ransom connected to the kidnapping. | Is killed by Peter during the exchange. |
| Kyle | Carrie’s partner and Milo’s other biological parent. | Is murdered by Rob. |
| Marissa Irvine | Raises Milo unknowingly, then engineers Peter’s fatal allergic reaction. | Is protected from prosecution by Detective Alcaras. |
| Colin Dobbs | Becomes involved through the debt and gun struggle. | Is accidentally killed by Carrie. |
Peter starts the chain by hiding the baby swap, but the series distinguishes that origin from each character’s individual choice to kidnap, threaten, shoot or kill.
What the ending means
A family built on unequal knowledge
Peter’s secret gives Marissa a family life founded on information she was denied. Carrie knows she has lost a child but not where he is; Marissa believes she is raising her own baby; Peter alone knows the exchange happened. The thriller’s suspense comes from that unequal distribution of knowledge rather than from a random kidnapping.
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Working motherhood and invisible labor
The mystery also sits inside a story about household pressure. Gallagher told the Associated Press that women are often expected to be “the CEOs of the household,” managing projects and delegating while working full-time. Sarah Snook said the appeal included the possibility of women’s friendship and mutual strength, rather than reducing the women to rivals.
Those pressures do not excuse Carrie’s crime or Marissa’s retaliation. They explain why the show treats the women’s decisions as shaped by grief, responsibility and systems that assume they will absorb every crisis.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is the TV ending the same as the book?
The series adapts Andrea Mara’s 2021 novel All Her Fault. Megan Gallagher has said the book supplied the adaptation’s central “tent poles,” while television expanded the surrounding material. The Wrap has also noted that Carrie’s death differs slightly between the novel and the series.
The confirmed overlap is the core premise—the missing child, the hidden baby-swap truth and the investigation around it—not an identical finale. Anyone comparing versions should treat the television ending as its own continuity; the available adaptation comments do not establish a complete scene-by-scene list of every change.
Quick Recap
Where everyone stands at the end
- Milo: alive, recovered and returned to Marissa, with his biological identity finally revealed to the audience.
- Carrie/Josie: dead before she can publicly complete her explanation.
- Peter: dead after his cover-up is effectively exposed to Marissa and punished by her.
- Marissa: still Milo’s mother in the life he knows, but now aware that Peter’s secret shaped the family.
- Detective Alcaras: chooses not to prosecute Marissa, making the finale’s law-versus-justice conflict explicit.
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