Harriet wonders if the man in the subway car really was following her. She tries to convince herself that it’s simply her paranoia, a byproduct of the post-traumatic stress disorder she has from the childhood loss of her parents. Harriet pays $140 for a tape-recorder player.

Harriet plays Robert’s tape. At first, it’s all muffled voices, and Harriet wonders if Robert has given her the wrong tape. Just as his voice comes on, Harriet’s phone rings. Amy from Greenville Sinclair is calling to give Harriet a new deadline. Harriet’s new book is due in two weeks. Amy has been told that Harriet has a book nearly completed, but Harriet only has three chapters. She decides to put Robert’s tape on hold so she can get some work done.

While Harriet is writing, she’s interrupted by a phone call from Eleanor. Eleanor wants Edward and Harriet to spend Christmas with the Holbecks at the family estate called The Hydes, but Eleanor is asking Harriet because she’s worried Edward will say no. Harriet says now is not a good time to ask Edward, but that she’ll keep the invitation in mind.

Eleanor sends a housekeeper to Harriet. The housekeeper is a Māori woman named Ataahua.

Harriet has never had a housekeeper before, and she concedes that Ataahua’s help around the apartment has given Harriet more time to devote to her writing. Various members of the Holbeck family keep calling Harriet to invite her to things. Edward warns that taking favors from the Holbecks is a slippery slope, but Harriet appreciates their attempts at making her feel cared for. Harriet is doing well with her deadline. She worries that the Holbecks will read her book and see a part of themselves in it; the new book is about a wealthy family with deep, dark secrets. Harriet has still not listened to Robert’s cassette tape because she is so focused on finishing her new book.

Harriet finishes her manuscript and sends it to her publishers. With her deadline met, Harriet meets with Lila. Lila tells Harriet about growing up in Sweden, becoming a model in New York, marrying a Bostonian basketball player and Milo’s birth, her divorce, and meeting Stuart. Lila appreciates that Stuart is sober. She says that Stuart is a good man and a good stepfather to Milo. Lila brings Harriet to Summit Vanderbilt, which gives them a fully glassed view of the city. Lila notes that it’s good to know that Harriet isn’t easily made afraid.

Fiona calls Harriet to invite her to their annual holiday party. Fiona tells Harriet that Billy has been insisting on Harriet coming. Harriet explains that the party is in honor of Krampusnacht, an ode to the Holbeck’s German ancestry. Fiona instructs Harriet to bring a battery-powered flashlight. Harriet looks up the history of Krampusnacht. Krampus is a monstrous creature who punishes children on St. Nicholas’s naughty list. On Krampusnacht, children receive presents if they’ve been good and nothing if they’ve been bad.

Edward explains that the Holbeck family’s Krampusnacht is filled with games for the kids. Sometimes, the games are scary. It’s meant to build character in the children. Edward calls Harriet a good person, which makes Harriet feel guilty. Harriet has her own 20-year-old secret that she believes proves she’s a bad person. She worries that Robert knows her secret.

Harriet starts listening to Robert’s cassette tape.

Robert blames himself for Bobby’s death. It would take weeks to figure out all the drugs that had been in Bobby’s system; originally, all Robert knows about Bobby’s death is that Bobby fell onto the street. Bobby wanted to prove to Robert that there was a new, better, more progressive way of doing things in life. A woman who knows the truth about Bobby haunts Robert, so he kills her and gets rid of her body. Robert’s voice on the tape assures Harriet that she’s not in danger but reminds her that he’ll do anything to protect his family.

Harriet pauses the tape. She is alarmed at what Robert is saying and what this might mean as a warning to her. She tries to calm down because she knows that her stress becomes the baby’s stress. Harriet goes for a walk. Harriet researches deaths by suicide on the Upper East Side and finds a photograph of a tent under the Holbecks’ townhouse. This confirms to her that Bobby jumped to his death rather than dying of an accidental overdose, like Edward told her. On her walk, she sees the same man from the subway car following her. She is certain that Robert has sent someone to follow her because of the tape he has given her. Harriet wonders if Robert’s tape is part-memoir, part-thriller. He may not have actually killed anyone himself, perhaps creating a fictive version of Bobby’s death. Harriet realizes that Robert “has chosen me because he likes games, because he likes thrillers, and because he has decided I am a worthy opponent” (128). Harriet researches photographs of the Holbeck family and finds photographs of their former nanny, a beautiful young blonde woman who matches the description of the girl Robert killed. The woman’s name is Samantha Belson.

Deonte Hughley, a retired NYPD lieutenant, meets with Harriet, believing that Harriet is doing research for her new book. Harriet tells him a hypothetical story about a woman listening to her father-in-law’s tape-recording confessing to a crime. Harriet isn’t sure if her fictional tape-recording is just a game or a real confession. She wants to know how much evidence her character would need before bringing it to the police. He explains that for someone in her character’s situation, evidence of a body would be best because it would protect her from the influence of the fictional family’s power. Deonte advises that Harriet’s character make a copy of the taped confession.

Harriet tries to find Samantha Belson online. She finds the real Samantha Belson, now 60 years old, on Facebook. She is still alive. Samantha agrees to meet with Harriet.

At the Krampusnacht party, Fiona warns Harriet that the night will be weird. She explains that after the kids unwrap presents, the Krampus will disappear. Harriet has been paired up with Billy, who requested her. Fiona can tell that Harriet is pregnant. Fiona is surprised that Edward would let Harriet come to the Krampusnacht party this early in her pregnancy. The game of the night begins, and Matilda gives Harriet a piece of advice for the game: She tells her to run for her life.

Billy tells Harriet they need to run and find a place to hide before finding an Evergreen stick. If the Krampus finds you and you show it the Evergreen stick, the Krampus goes away, and you win the game. Krampus arrives at the party. Harriet is terrified to see that the Krampus is horrifying and realistic. She picks up Billy, and the family locks them out of the sitting room. Harriet runs away from the Krampus by going up the stairs. Though she’s rational and knows the Krampus is someone in a realistic costume, she finds the whole thing genuinely scary. Harriet finds Tristan and Olivia, Fiona’s niece and nephew. They’re paired up and look terrified. Harriet instructs them to team up with her, but she loses them. She hears Milo’s screams and notes that they sound real and truly terrified. Billy is so scared that he pees himself. Billy and Harriet continue moving up the stairs of the house. The top floor of the house is one huge playroom. Harriet blocks the door of the playroom and assures Billy that they’re safe. Harriet finds a wardrobe of clothes and changes Billy. Olivia and Tristan knock on the door, and Harriet unblocks the door to let them in, then blocks the door after them.

Harriet asks Olivia what clues there are to win the game. Because they’re on the top floor and no one has found the Evergreen stick yet, Olivia figures it’s hidden in the basement. The game can’t end until the stick is found. Olivia says that the clue is the name of the oldest player; in this case, the clue is hidden in the letters of Harriet’s name. Harriet and Olivia try to figure out an anagram with Harriet’s name. Harriet uses her last name, Reed. She figures out that the clue is “hereditary.” Olivia thinks that the clue signals to a placard in the basement that everyone in the family has inherited, a placard from the original Holbeck’s first home. Billy tells Harriet she can secretly get to the basement by using the hatch.

Harriet goes down the hatch and finds the basement. She sees the placard and the Evergreen stick behind it. She reaches for the stick and it falls to the ground. She hears a voice breathing in the hatch with her and realizes that the Krampus is there with her. She turns on her flashlight to find the stick. Just as she grabs the stick, the Krampus nails her against the wall and touches her. She elbows the Krampus in the face, yells out Evergreen and wins the game. Lights go on, and everyone celebrates. The Krampus is revealed to be a CGI actor in detailed costume. Harriet confronts Fiona about the game and scaring her own son. Fiona explains that she wasn’t allowed to tell Harriet the details of the game because the point is to test the new people and to work with the family intergenerationally as a way of proving one’s capacity for teamwork and fortitude. Fiona and the others had been watching the game the whole time on security cameras. Fiona knows her son Billy was scared, but she also knows that he was safe.