Birdy and Carter leave dinner with the excuse that they’re attending the Day of the Dead parade. As they wind through the throng of parade attendees, all in costume, Carter notices that the pub is closed and makes a note to check on Maddy. When they reach Spyglass House, Mary’s red Mini is parked outside. Carter notes that Birdy’s grandmother’s caregiver drove the same car. Diana Harris emerges from the house, claiming to be visiting Harrison to bring him dinner.

Harrison meets them at the door and at first won’t let them in without his lawyer. Birdy says they have enough evidence to arrest him. He claims that they’re “wrong about everything,” but lets them inside. Carter sees two packed suitcases, and the house is dimly lit and eerie. Carter hated Birdy’s grandmother because she owned the Smuggler’s Inn and sold it when she became ill, ruining his family’s business. Carter receives a text with the coroner’s report.

The coroner can’t identify the body and will need to wait for dental records. The hair in the brush is not the same as the body’s. Harrison demands they leave now that they have proof he didn’t kill his wife. Carter and Harrison begin arguing and hurling insults. They begin fighting, and Birdy breaks them up, threatening to arrest Harrison. She sends Carter outside and says she’s “calling for backup.”

Harrison says Birdy can’t arrest him. He has recently put up a photo of Gabriella in place of one of Eden. Birdy sees the photo and recognizes Gabriella.

When Birdy was “a junior detective,” she was out having drinks with friends. She got the call about a missing child and drove swiftly to investigate. It was raining, and her phone rang. She answered it, and in her distraction, she hit Gabriella. Afterward, Birdy changed jobs, gave up alcohol permanently, and has carried the guilt ever since. She fears that Harrison never forgave her.

Carter waits outside Spyglass. He is worried about Maddy and checks his phone. There’s a message from headquarters stating that Detective Chief Investigator Bird can’t suspend him because she has retired and isn’t his boss.

It is November 2, 2025, the day Thanatos told Birdy was her “deathday.”

Carter races back inside Spyglass House, but Birdy and Harrison are nowhere to be seen. He enters the library and sees a copy of Frankenstein on the floor, which reveals the secret door behind the bookcase. Just as he is about to enter the tunnel, someone hits him on the head, knocking him unconscious.

Harrison loads the suitcases in his Porsche and drives to The Manor to pick up Gabriella. While driving, he contemplates the mistake he made in creating Thanatos. He based the algorithm on NHS records of people’s illnesses. The purported cutting-edge technology is merely the ability to access medical data and make educated guesses based on existing health conditions. Creating the company put a lot of strain on Harrison, and he had a near-fatal heart attack. It was then that he realized that Thanatos had incorrectly predicted his death date, and each time he ran the algorithm, it returned a different date. Harrison realizes that giving people their end date is harmful to humanity and decides to sell the company and then destroy it.

Harrison reassures himself that although he had the desire to kill Eden, he isn’t responsible for her death. He calls The Manor and instructs them to pack Gabriella’s things, but she has gone missing. A woman’s hand touches his shoulder, and he hears, “I love you to the moon and back” (269).

Carter thinks he is dreaming when he hears Birdy speaking to him. They are in the tunnel, and it’s dark, so he can’t see her face, only the tattoos on her arm. She tells him that Mary explained to her that she had cared for her grandmother for two decades, and when her grandmother died, she didn’t leave her the house. After the new owners moved in, Mary returned to claim “what she believed was hers” (271). Mary also revealed that when Birdy was a child, she found the secret tunnel and became lost, which led to the rift between Birdy’s grandmother and her mother. Birdy says she must leave because her time is running out, but that Carter should take the tunnel to the beach. She kisses Carter goodbye, and he thinks her voice sounds strange.

Birdy exits the tunnel and reenters the house. She closes the secret door and rests on the floor as she feels weak. Carter yells from the other side, and Birdy tells him that she is the one who knocked him unconscious. She has taken his phone.

The narrative flashes back to six months prior. After Birdy receives her letter from Thanatos, she quits her job and plans how she will spend her remaining time with Sunday. She resolves that she must see Gabriella one last time and travels to The Manor. Mary guides Birdy to Gabriella’s room, explaining that she hasn’t spoken but enjoys painting. What Gabriella paints reflects her mood, as a wolf represents being sad, a fox means she’s afraid, and a bird means she’s happy. When Birdy enters the room, Gabriella says, “Mummy.”

In the present, Birdy reveals to Carter that she was Harrison’s first wife. After Gabriella’s accident, Birdy left because she thought it was her fault. Eden was their nanny, and she moved in after Birdy left. Eden became Harrison’s second wife and Gabriella’s stepmom. Birdy believed it was for the best until six months ago, when she visited Gabriella and learned the truth. Carter asks if Birdy killed Eden, and she replies, “No. I just wish that I did” (231).

Birdy explains that when she began visiting Gabriella, Gabriella began whispering the truth to her. On the day of Gabriella’s accident, Gabriella was playing hide-and-seek when she saw Harrison having sex with Eden. Later, Eden pushed Gabriella down the stairs, severely injuring her. She took Gabriella outside and staged the accident. The phone call to Birdy was Eden’s attempt to distract her, making it seem as if Birdy had hit Gabriella. After learning the truth, Harrison, Birdy, and Mary planned to lure Eden to the cliff, push her over the side, and erase all evidence of her existence. Mary would then move in and become the new Eden. Birdy was supposed to push Eden over the cliff, but someone else did.

Birdy says she is dying, but Carter already knows, having seen the pills she’s taking. The same ones his mom takes for her cancer. Since the coroner’s report still hasn’t proven that the body is Eden’s, Carter is skeptical. He wonders whether Gabriella is “misremembering” or “lying,” but Birdy says this is impossible because Gabriella is still mentally a child.

The narrative flashes back to the night after Carter’s visit to the Manor. Gabriella escapes, hides inside Mary’s car, and falls asleep. Gabriella reflects on her “first mummy,” Birdy, and her “second mummy,” Eden. She thinks Mary might become her third, but she wants to live alone with her father. When she reaches from the back seat and touches him on the shoulder, it scares him. Mary is in the passenger seat. Gabriella leaps from the car and runs away.

In the present, Birdy urges Carter to run, but he needs more information. Birdy explains that the three of them had a plan to get “revenge for one thing or another.” The original plan was to throw Carter off the trail as much as possible, but he has proved a better investigator than they thought. With Eden dead, Harrison is in love with Mary and plans to escape overseas with her and Gabriella. Harrison has purchased Smuggler’s Inn so Carter’s family can own it outright. In exchange, Carter must lie about all that has happened.

Carter isn’t convinced that Eden is dead and isn’t sure he’s willing to lie. Birdy plans to die by suicide with pills so she can exit on her own terms. After she takes the pills, she thinks she’s dreaming when she sees a woman dressed as a skeleton bride standing over her, saying “I hate you […]” (294).

Carter meanders through the tunnels and emerges on the beach where the townspeople are having a Day of the Dead bonfire. He sees Maddy, and she explains that a power outage is to blame for Smuggler’s Inn being dark. Carter pleads with Maddy to come to Spyglass to help him. When they get there, Birdy is unconscious. Maddy calls an ambulance while Carter administers CPR and begs Birdy to stay alive for her daughter. Birdy is unresponsive, with no pulse.

One year later, Birdy is still alive. She survived her suicide attempt because of Carter’s lifesaving efforts. Her cancer is in remission, and she lives at Spyglass House with Sunday. Harrison lives in Switzerland with Mary and Gabriella, but Gabriella often visits Birdy. Carter’s parents returned from Spain, and he got the promotion. Birdy takes Sunday out for a run, but when she returns, the door is locked. Gabriella is there, and she locks the door sometimes. Birdy has forgiven Harrison for what happened with Eden because he financially supports her and Gabriella.

Jane admits she pushed Eden off the cliff because she was jealous of her relationship with Carter. Jane was the skeleton bride who appeared at Spyglass. Jane had intended to kill Birdy, too, but thought she was dead. She knows Carter is hiding their affair and admits she “still might.”