Marissa arrives at 14 Tudor Grove to collect Milo and finds only an elderly stranger named Esther answering the door.

Marissa calls the police after confirming Milo is not at the arranged address and she cannot reach Jenny Kennedy.

The school principal confirms that Jacob's nanny, Carrie, collected Milo from school on the day he disappeared.

Jenny returns from Paris and is questioned by detectives about her nanny Carrie, describing her as quiet and harmless.

Police locate and interview Irene, Carrie's estranged mother, who lies about her ex-partner Rob Murphy's current location.

Milo's raincoat is found near the sea and detectives send out the coastguard, fearing Milo has drowned.

A witness reports seeing a man deliberately throw Milo's raincoat near the sea to mislead the police investigation.

Milo is found unattended in a parked car in Sandymount by a newspaper deliveryman and brought to the police station.

Lia shows Marissa a Facebook photo in which Colin Dobson can clearly be seen on a date with Carrie.

Detective McConville reveals that murdered man Danny Vaughn is actually Kyle Byrde, Carrie's boyfriend, whose body was mutilated to hide his identity.

Police discover Carrie's body in the Sandymount house where Milo was held; she was smothered to death with a pillow.

Marissa reviews the client files and discovers that her business partner Colin has stolen over 560,000 Euros from their accounts.

Colin and Rob Murphy are found shot dead, with evidence suggesting each man shot the other before dying.

Peter confesses to murdering Carrie, staging Milo's rescue, blackmailing Colin, and killing Rob Murphy to conceal his crimes.

Peter reveals he switched the babies at the original crash scene, taking Carrie's living son and leaving his own dead infant.

All Her Fault opens with Marissa Irvine arriving at a stranger's door instead of finding her son Milo safe at his playdate, setting off a frantic investigation. The police quickly identify Carrie, the nanny of Jacob Kennedy, as the person who collected Milo from school under false pretenses. False leads — including Milo's raincoat found near the sea — raise the stakes before Milo is finally discovered unharmed in a parked car in Sandymount. As detectives unravel the conspiracy, a photograph links Carrie to Marissa's business partner Colin Dobson, and the murdered man Danny Vaughn is revealed to be Kyle Byrde, Carrie's criminal boyfriend. With Carrie found smothered to death and Colin and Rob Murphy shot dead, the truth finally emerges when Peter Irvine confesses to multiple murders — and to having swapped babies at the original car crash scene four years earlier.

The kidnapping, investigation, and Peter's confession.

Jenny interviews Carrie for the nanny position, and Carrie successfully presents herself as shy, quiet, and completely harmless.

Jenny and Marissa meet at a school fundraiser, discover they wore the same dress, and agree to arrange a playdate for their sons.

Marissa receives a text she believes is from Jenny arranging a playdate for Milo at 14 Tudor Grove.

Ana returns to Marissa's house to collect her forgotten phone and is devastated to learn Milo has gone missing.

Jenny searches Carrie's bedroom and discovers a photograph of Kyle Byrde, whose online record reveals a long criminal history.

Jenny visits Marissa at Maple Lodge to offer support and agrees to help distribute missing-child flyers around the area.

Irene wakes to find her daughter Caroline pictured in the news as the prime suspect in Milo's kidnapping.

Irene meets a tabloid journalist at a café and agrees to sell her story about Carrie for money.

Ana confesses to police that she befriended Carrie and unknowingly shared details about the Irvines' daily routines and home life.

An elderly man tells Jenny and Marissa he saw Milo walking calmly alongside Carrie on the day of the kidnapping.

Marissa and Peter visit their office late at night, and Peter finds hidden pages behind a printer that visibly shock him.

Names on Jacob's bedroom chalkboard lead Jenny to identify 'Dani Von' as Danny Vaughn, Carrie's known associate, and she alerts the police.

Brian admits to Marissa his secretive behavior was due to a hidden affair with a woman who is already engaged.

Richie confesses to Jenny that anonymous notes alleging her affair with work colleague Mark have been arriving since August.

Marissa and Jenny meet for coffee after the crisis ends, choosing to remain friends despite the painful way they were brought together.

Before Milo's disappearance, Carrie carefully inserted herself into his world by winning the job as Jacob's nanny and befriending Ana, Milo's own nanny, to gather intelligence on the Irvines. Jenny and Marissa's friendship began at a school fundraiser, an innocent meeting that would set the entire kidnapping plot in motion. As the investigation unfolds, key clues emerge from unexpected places: a criminal's photograph hidden in Carrie's room, names scrawled on a child's chalkboard, and Ana's reluctant confession about her friendship with Carrie. Throughout the crisis, Jenny serves as Marissa's most steadfast supporter, distributing flyers and offering comfort even as the stress drives Marissa to collapse in the street. Long after the case is closed, Marissa takes justice into her own hands by engineering Peter's death from his shellfish allergy during their Spanish vacation.

The nannies, the families, and the clues hiding in plain sight.

Jenny watches an American TV show and realizes Carrie invented her entire personal history by copying the show's three brothers.

Richie stands up to his mother Adeline and tells her to leave after she blames Jenny for Milo's kidnapping.

Marissa collapses onto the pavement while distributing flyers with Jenny, overwhelmed by despair about Milo's captivity.

Neighbor Joe Downey tells Jenny he saw Kyle Byrde enter the Kennedy home several times while Jenny and Richie were at work.

Sergeant Sheridan interviews Milo, who describes a red-brick house with a white door and one gray step, helping police narrow their search.

Peter claims an unknown woman phoned to say someone close to the Irvines helped Carrie plan the kidnapping of Milo.

Carrie disguises herself as the glamorous persona 'Lena' and goes on a date with Colin Dobson to extract details about the Irvines.

Milo becomes distressed at school when he hears children playing nearby, revealing his captors held him close to an active schoolyard.

Jenny re-reads her nanny job advertisement and realizes Carrie deliberately targeted her family to gain access to Kerryglen National School.

Marissa and Peter confront Colin at his home; he admits dating a woman called 'Lena' but denies knowing she was Carrie.

Marissa notices that despite appearing to cry and apologize at length, Colin has no actual tears in his eyes.

Milo tells Marissa the masked man who abducted him from Carrie's house used Peter's private nickname for him.

Carrie and Rob reunite in London, where Rob discovers Peter lied about fault in the crash and Carrie's baby had survived.

Carrie spots Milo and Peter at a playground, bonds with Milo over their shared synesthesia, and confronts Peter about the baby swap.

Marissa realizes synesthesia is heritable and, since neither she nor Peter has the condition, Milo must be Carrie's biological son.

Beneath the kidnapping case lies a web of turning points and concealed truths that gradually reshape the entire story. Jenny's realization that Carrie invented her personal history by copying an American TV show is one of the first cracks in Carrie's false persona, while Milo's slow, fragmented interviews with a specialist detective inch the investigation toward the hiding house. As the mystery deepens, Peter engineers a suspicious anonymous phone call to direct suspicion toward Colin, and Marissa begins to see through Colin's tearless performance of guilt. Flashbacks revealed near the novel's end show that Carrie confronted Peter at a playground years before the kidnapping after recognizing their shared synesthesia in Milo, and that her father Rob had long known the baby swap was no accident. Marissa's final devastating realization — that she and Peter both lack the heritable condition their son has — confirms everything Peter has done and seals his fate.

The hidden truths, key decisions, and shocking discoveries that unravel the mystery.