A flashback reveals that Jon took Savannah’s car keys to prevent her from driving to his house and revealing their affair to Susan. When Savannah lunged for them, Jon grabbed her wrist and left marks. She threatened to take a taxi or call the police.

During the confrontation, Greta called Jon about Susan’s surprise party. Savannah assumed that it was Susan calling and offered to speak to Jon’s wife. Desperate, Jon pretended that Greta was Susan and confessed the affair on the phone. Greta realized what was happening and played along to protect her sister. Savannah remained unconvinced, so Jon asked Greta to come in person and impersonate his wife. Greta reluctantly agreed, making it clear that she was doing it for Susan, not him.

Greta arrived at Savannah’s house, and Jon introduced her as Susan. Jon explained their open-marriage arrangement to Savannah. Greta, posing as Susan, said she didn’t care what Jon did as long as no drama reached her doorstep, citing their baby and her job at the local school. Greta then sent Jon to work, saying that she would have coffee with Savannah to make sure they were “on the same page” (302). Jon departed, leaving Savannah alone with his supposed wife.

On the same Wednesday morning, having not slept since discovering Aimee’s body and killing Rory, Venetia sent a threatening text to Susan using Felipe’s old phone.

At lunchtime, two gardaí arrived. Officer Orla informed Venetia that bodies believed to be Aimee and Rory were found, both killed with a barbell weight. The garda observed that the attacker would have been in proximity to the victims due to the murder weapon’s small size. Venetia was puzzled since the barbell kept her several feet from Rory as she killed him. The officers requested DNA samples to eliminate Venetia and Felipe from the investigation. Venetia feigned illness to end the interview. Afterward, she asked Felipe why the gardaí believed that only the weight disk was used. He told her not to worry, and she fell asleep, exhausted.

Nika drives away from Oakpark, believing that no one witnessed her hit Maeve. Realizing that she needs an alibi, she pulls over and posts gallery photos from Jess’s bedroom to Snapchat to place herself there. Nika then turns off her location and drives back to Jess’s house.

Jess doesn’t answer, and Nika can’t knock without revealing she left. She decides to drive to Ariana’s nearby house instead. As she passes the Oakpark turnoff, she hears sirens growing louder and accelerates in fear.

A flashback reveals that, after Jon left, Savannah asked Greta whether her marriage was open, as Jon claimed. Greta confirmed that the arrangement wasn’t ideal but worked for their baby, Bella, who was unplanned. When Savannah mentioned that another woman had aggressively confronted her the previous night, Greta was surprised, wondering if Jon was seeing multiple women.

When Greta said she had to leave for hockey camp, Savannah asked who was looking after Bella. Greta became flustered and said her sister. Savannah pressed for the sister’s name and noticed Greta’s growing discomfort. When she asked why Greta wasn’t on maternity leave, Greta struggled to answer. Savannah noticed that Greta wasn’t wearing a wedding ring and realized she wasn’t Susan.

Maeve lies unconscious in Oakpark, having landed six feet from where Nika’s car struck her. Her head hit the concrete on impact. Without medical attention, she will die. No one knows where she is as she lies under an oak tree.

Greta admitted to Savannah that she was Susan’s sister. She tried to discourage Savannah from contacting Susan, explaining that her sister was already dealing with a threatening message and a smashed window. Savannah laughed and confessed to throwing the brick. Greta was furious, pointing out that Bella’s cot was near the window. When Savannah callously said that Bella was not her concern, Greta slapped her. Savannah ordered Greta out or threatened to call the police. Greta left but warned Savannah to stay away from Susan and Bella. Alone and fuming, Savannah looked for her phone, remembering that Jon still had her car keys. She then heard someone at the front door.

On Thursday evening, Venetia sees an Instagram post of Susan at a family meal, smiling and holding Bella. Rage consumes her. As she grabs her car keys, Felipe tries to stop her. She runs upstairs, retrieves a syringe from a hidden shoebox, and pushes past him. Felipe reveals that he unscrewed the bar from the barbell after Venetia left Rory’s house and hid it in the roof gutter. Consequently, the gardaí think that only the weight disk was used, and they won’t find her DNA. He physically blocks the door, but Venetia violently yanks him aside and drives off. She ends up in Susan’s kitchen, holding Bella.

Maeve regains consciousness to find Cody Geary leaning over her, calling an ambulance. She remembers hearing a car engine revving before the impact. Nearby, she spots a silver, jaguar-shaped hood ornament. Moira Fitzpatrick then arrives and yanks Cody away, accusing him of attacking Maeve. Cody says that he already called an ambulance. Maeve hears a siren and loses consciousness again.

Nika goes to Ariana’s house to establish an alibi and offers a practiced apology for dating Zach behind her back. Ariana says that she wasn’t bothered about Zach, but she confronts Nika about posting Maeve’s diary pages online and refuses to let her in.

Back at her car, Nika notices that the silver jaguar hood ornament is missing. Upon returning home, Nika hears Cody run upstairs, upset, and then the doorbell rings. Spying from the landing, she sees Moira Fitzpatrick and overhears that Maeve is in the hospital. Nika assumes that Maeve has identified her as the driver. She considers confessing but then hears something that changes her mind.

Moira arrives at Celeste’s door to say that Maeve is hospitalized and that Cody attacked her. She found Cody leaning over a semiconscious Maeve and has called the gardaí. Celeste defends Cody and glances up to see Nika watching from the landing. Two gardaí arrive, saying that they’re investigating a hit-and-run and need to examine Celeste’s car. Relieved—thinking that this absolves Cody since he doesn’t drive—Celeste explains that Cody is 15 and has never driven and that Nika had the car that evening. She immediately realizes the implication of her own words.

Susan finds Venetia in her kitchen holding Bella improperly by one arm, with Greta unconscious on the floor. Venetia threatens to harm Bella if Susan approaches, brandishing a tire iron and a knife. She tells Susan that Rory saw Susan’s message and beat Aimee to death that night.

Greta, now conscious and kneeling, tries to reason with Venetia, who gives Susan a terrible choice: sacrifice either Bella or Greta. When Greta tells Susan to sacrifice her, Venetia insists that Susan must say the words herself. Crying, Susan chooses Greta’s death to save Bella. Venetia reveals a syringe of liquid heroin and orders Susan to inject Greta. As Greta calmly prepares her arm, her bag falls into her lap, and her eyes try to convey a message that Susan doesn’t understand. Susan picks up the syringe.

Susan injects Greta, who collapses and appears dead. Susan demands Bella back, but Venetia smirks, pushes open the back door, and says that she’ll keep the baby until she’s bored, threatening to cut Bella if Susan follows. Susan runs after Venetia and sees her car screeching away. She runs after it, screaming Bella’s name, and then hears a crash. Susan twists her ankle but keeps running toward the collision.

Dazed after the crash, Venetia realizes that Felipe deliberately swerved his car in front of hers to stop her. She grabs the tire iron and knife and pulls Bella from the back. As Felipe stumbles toward her, bleeding from his head, Venetia strikes him across the temple with the tire iron, and he collapses.

Seeing Susan and others running toward her, Venetia lays the baby on the ground. She tells Bella that she’s about to make Susan suffer for the deaths of Aimee and her baby. She smiles at Susan and raises the knife high over Bella.

Susan is too far away to reach Bella in time. Felipe, still on the ground, throws himself over the baby to shield her. The knife plunges into his back. Susan reaches them as Venetia tries to extract the knife. She grabs the tire iron and strikes Venetia across the head, knocking her unconscious.

Felipe rolls aside, revealing Bella alive beneath him. Susan pulls Bella into her arms as neighbors gather. Felipe explains that he went to Leesa’s house looking for Venetia and then returned, saw Venetia’s car, and swerved to stop her. Susan screams at a neighbor to run to her house and call an ambulance for a heroin overdose. She then tries to keep Felipe awake, telling him he must be Bella’s guardian. Felipe whispers that Susan is “a great mother” and asks her not to let go of his hand (343). He closes his eyes and takes his final breath.

Early on Friday morning, Jon finds Susan at the hospital with Bella unharmed. The gardaí have questioned Jon about Savannah’s death; a text from her that he received while he was at work provided an alibi.

A doctor explains that Greta survived because she had taken a handful of naltrexone tablets, the medication she takes for long COVID, before the heroin injection. She faked a dramatic collapse to convince Venetia. Susan processes that Bella and Greta are alive, that Maeve is recovering, and that Felipe is dead.

At four o’clock in the morning on Friday, Celeste, Warren, and Nika return from the garda station. Nika has been charged with Section 3 assault. Cody, waiting up, asks if Nika will go to prison. Warren explains that the charge is serious but that courts try to keep young people out of jail.

Cody whispers that he doesn’t want Nika imprisoned and confesses that he feels inadequate and bad at everything. Punching the wall briefly made him feel better. He admits that he considered using a knife on himself. Celeste realizes that she missed the signs of self-harm and apologizes for failing both her children, promising she will be there for them now.

On Sunday, Susan and Leesa visit Greta in the hospital. After Leesa leaves, Greta tells Susan that she believes Maeve put the almonds in Nika’s lunch because she saw something on Maeve’s laptop about spiking food. A neighbor also mentioned seeing Maeve in a hoodie and hat near the changing rooms, even though she wasn't playing hockey. When caught checking Nika’s lunch bag, Greta took the blame because Maeve is family and just a child.

Susan apologizes for injecting Greta with heroin. Greta insists that she would want Susan to do it again. She hadn’t known for certain that the naltrexone would stop the heroin from killing her but hoped that it would based on its use as an overdose antidote. Susan reflects that none of them intended the consequences of their actions but remains unsure if that’s sufficient for forgiveness.

Susan keeps Maeve company in the hospital while her parents eat. Maeve urgently tells Susan that she hates Nika but would never spike her lunch, and she’s scared that Greta did it after seeing her laptop search history. Susan reassures Maeve that Greta definitely didn’t do it and suggests that another student may be responsible. Relieved, Maeve makes Susan promise not to tell Greta that she suspected her.

Outside, Susan encounters Celeste, who sobs with relief when Susan confirms that Maeve will be fine. On impulse, Susan hugs her, and they cry together over their struggling children. Celeste asks about Bella, and Susan says that she’s safe at home with Jon. Susan reflects that her marriage is over, though no one yet knows who killed Jon’s mistress.

A flashback to the previous week reveals that a man rang Savannah’s doorbell with a parcel. Before heading downstairs to answer it, Savannah looked at the rose-gold bangle she had replaced after losing the original that Jon bought her. Reflecting on its meaninglessness, she threw it in the bin.

In the downstairs hallway, Savannah didn’t notice a puddle of rum on the floor. Her new, slippery ballet flats slid out from under her, and she fell, her head striking the corner of the radiator. Outside, the man realized that he had the wrong house and left.

Greta reveals that the inquest’s story about Savannah slipping on rum in the hallway is plausible but untrue. She recalls how, after Susan first mentioned Savannah, Greta looked her up and recognized her. Years earlier, Greta had been in a car accident that left her with a permanent limp. The other driver was Albie Byrne, Savannah’s husband at the time. Through Albie’s sister, Greta later learned that Albie had broken his ankle skiing the week before the crash and couldn’t have been driving. Greta deduced that Savannah had been driving drunk and that Albie covered for her.

When Jon asked Greta to impersonate Susan, she saw an opportunity to confront Savannah. After slapping Savannah for her callous remark about Bella and leaving, Greta sat in her car and then returned to confront Savannah about the accident. Savannah admitted the truth and said she was “delighted” that Greta had been permanently injured. Enraged, Greta pushed her. Savannah hit her head on the radiator and died.

To protect herself and Jon, Greta staged the scene as an accident. She spilled more rum on the floor and then texted Jon from her own phone to confirm that he was at his office, securing his alibi. She sent a final text from Savannah’s phone to Jon’s burner phone mentioning harassment by her ex-husband and then changed Jon’s contact name to “Sam” to misdirect investigators. She later gave Jon a fictional version of events, and he never suspected her guilt. Greta reflects that Savannah is more accurately “an accident victim” (365), much like herself.

One year later, Susan has wine with Celeste. Nika has been living in West Cork since September, completing her sixth school year away from Oakpark while awaiting her court appearance. A custodial sentence is possible, though their lawyer believes that Nika’s age, guilty plea, first offense, compensation paid, and apparent remorse may keep her out of detention. Cody has improved. Celeste and Warren have separated. The identity of the person who spiked Nika’s brownie has never been solved. However, when Susan compliments Aoife on her distinctive, brightly colored hat, Aoife reveals that the hat is Maeve’s. Taking it off and stuffing it in her bag, Aoife casts a guilty look toward Celeste.

Susan and Jon have also separated amicably, and Susan has stayed in Oakpark, where life has moved on. She continues counseling and struggles most with guilt over Felipe’s death.

After Celeste leaves, Juliette sends an insensitive message to the Oakpark group, joking about how the previous year’s event was notable for the “ambulance lights” rather than the fireworks. Livid, Susan screenshots it and begins typing an angry response. She stops, takes a breath, deletes the message, puts down her phone, kisses Bella, and picks up her book.