Inside the Hiemses’ apartment, Elizabeth finds nothing for a while. Then she hears a thumping sound from a back bedroom and discovers the Hiemses’ long crate on the bed with something moving inside. As she tries and fails to open the sealed crate, “the feeling” draws her to a stack of papers. She finds a seven-year-old letter to Selena revealing that the crate contains the “mortal shell” of Selena’s mother, Gracella Winters, suspended in a state close to death. The letter explains that Gracella’s spirit separated from her body to recover its power and that Selena must care for the body until they can be reunited.

Elizabeth flees and explains her discovery to Freddy, realizing the crimson light they’ve seen is Gracella’s spirit. To get Norbridge to investigate, Elizabeth invents a story about the Hiemses having a puppy in their room but, when she checks with Norbridge shortly after, he reports finding nothing unusual. Frustrated, Elizabeth wanders into the portrait gallery and sees that the painting of Nestor Falls is signed by R. S. Granger—the author of The Book. Suddenly, Selena appears behind her.

Selena Hiems Elizabeth, demanding if she has solved the code in the portrait. Elizabeth accuses Selena of theft and trying to resurrect Gracella, then flees. On her way to find Norbridge, she sees Marcus carving symbols into the wall of the closed bridge.

Elizabeth finds Norbridge and urgently explains that the Hiemses are trying to bring Gracella into Winterhouse. When he seems skeptical, she confesses everything. Norbridge listens but still dismisses her urgency, asking a hotel worker to escort her to his apartment. He commands her to stay there until he comes for her, leaving her feeling ignored and anxious.

After falling asleep in Norbridge’s apartment, Elizabeth wakes to find three hours have passed. While eating a sandwich left for her, she accidentally uses “the feeling” to knock her plate off the table. The sensation lingers, and her pendant warms against her skin. The mysterious silver letters from The Book return to her mind, and she realizes they spell “THE KEY IS AROUND YOUR NECK” (374).

Now understanding that the word “Faith” on her pendant is the keyword, she deciphers the Vigenère code from Nestor’s portrait. The decoded poem instructs anyone holding The Book to vanquish evil by saying, “I choose the good” (321). Wondering about her necklace’s origin, she notices Norbridge’s bedroom door is ajar. Inside, she sees a family portrait in which Norbridge’s daughter, Winifred, is wearing the same pendant. Elizabeth races out of the apartment to tell Norbridge.

Elizabeth bursts into the New Year’s Eve party. She finds Freddy and explains how she solved the code. Unable to locate Norbridge, Elizabeth feels a sudden certainty that they must go to the library.

The library is dark, but they spot a crimson glow on the third level. Fearing Norbridge is in trouble, they ascend the stairs. In the reference room, they find Gracella Winters—the woman Elizabeth now recognizes from her nightmares—sitting in a chair, bathed in the eerie light. Gracella reveals that her “dear brother” is there as well, and Elizabeth sees Norbridge lying unconscious in a corner. Gracella gloats that they have come to her, saving her the trouble of hunting them down. Enraged, Gracella begins throwing books, and Elizabeth yells for Freddy to run and get help.

Alone with Elizabeth and the unconscious Norbridge, Gracella reveals that Elizabeth’s own power awakened Gracella’s spirit, allowing it to reunite with her physical body. Gracella also reveals that Selena located Elizabeth when her powers began, paid her aunt and uncle money to send her away, and arranged to have her brought to Winterhouse. Gracella pulls out A Guide for Children and gives Elizabeth 10 seconds to tell her what she knows about its secrets. To stall for time, Elizabeth begins explaining the code while secretly using “the feeling” to move The Book away from Gracella. Gracella senses Elizabeth’s power and offers her a chance to join forces, and Elizabeth feels tempted for a split second. When Norbridge groans, Elizabeth remembers her purpose. The Book flies into her hands, and she shouts, “I CHOOSE THE GOOD!” (342).

The crimson light vanishes, and Gracella weakens and collapses, thrashing violently before falling still. Norbridge wakes as Elizabeth, overwhelmed, bursts into tears. She shows him her pendant, saying, “I think Winnie was my mother” (344). Norbridge recognizes the necklace he once gave his daughter, Winifred, confirming Elizabeth is his granddaughter just as help arrives.

Elizabeth, Freddy, Norbridge, and Leona stay up until 3 am discussing the night’s events. Elizabeth explains how she solved the code and discreetly avoids revealing her telekinetic powers, implying Gracella knocked The Book over. She also reveals she has returned The Book to its hiding place. Norbridge tells them that, immediately after leaving the library, he had Jackson check the Hiemses’ room, but they were already gone and their room cleared out completely.

He and Leona tell Elizabeth about her mother, Winnie. They explain that Winnie left Winterhouse at 18, fearing the story of The Book was a curse that could endanger any child she had. She changed her name and disappeared, and Norbridge lost all contact with her, never knowing he had a granddaughter. Later, alone with Norbridge, Elizabeth asks about his “magic,” and he confirms that, as members of the Falls family, they both possess it.

Elizabeth spends her last four days at Winterhouse enjoying activities with Freddy and learning more about her mother from Norbridge and Leona. The night before her departure, she borrows the master key again and unlocks Gracella’s old room. The room is plain, but “the feeling” comes over her, and a sound draws her to a book in a bureau: The Secret Instruction of Anna Lux by Damien Crowley, about a girl who wants to be a witch.

At a farewell breakfast, Norbridge promises he intends to arrange for Elizabeth to return to live at Winterhouse, though he acknowledges there are guardianship rules he must navigate first. He also shows Freddy a letter from his parents, who plan to spend the next Christmas at the hotel with him. After an emotional goodbye, Norbridge walks Elizabeth to the bus, giving her a wrapped gift and advising her to protect her power, “be vigilant, be strong, be good […], and keep the faith” (368). On the bus, she unwraps the present: another book by Damien Crowley, The Secret of Northaven Manor. She opens it and begins to read with pleasure.