Chapter Forty: The Videotape Reveals a Horrifying Truth

⚠️ Spoiler Warning: This guide contains detailed spoilers for the entire novel. Proceed only if you've finished reading or are comfortable knowing the plot.

Summary

Isabelle slams her bedroom door and locks herself inside after returning from Paul's house. Waylon wakes up and knocks, worried because he heard her come in around two in the morning. She claims she needed air. He notices she is sweating and pale, but she insists she is fine. When she asks what the detective, Dozier, told him earlier, Waylon defers the conversation to morning. He leaves and locks his door, making Isabelle wonder if he is afraid of her as her mother once was. Alone, she opens her laptop and replays the nursery video. For the first time, she sees her sleepwalking self pick Mason up from his crib. Horrified, she slams the laptop shut before watching any further.

Key Events

Isabelle returns home late at night after visiting Paul, deeply shaken.
Waylon confronts Isabelle about being outside, but she deflects.
Isabelle asks about Waylon’s conversation with Detective Dozier; he puts it off.
Waylon locks his bedroom door, prompting Isabelle to recall her mother’s fear of her.
Isabelle rewatches the nursery video and sees her unconscious self lift Mason from the crib.
She closes the laptop in terror before seeing what she does next.

Character Development

Isabelle: Her reliability as a narrator crumbles completely. The video evidence contradicts her earlier certainty that she never touched Mason. Her fear shifts from external suspects to herself, and she begins to question her own mind.
Waylon: His locking the door reveals a cautious side we have not seen. He sets a boundary with Isabelle, suggesting he either senses danger or is protecting himself from her—or from something he learned from Dozier.
Mason: Though absent, his presence in the video makes him a symbol of vulnerability. The act of being picked up transforms him from a missing child into a victim of his own mother’s unconscious actions.

Themes, Symbols, or Motifs

Sleepwalking as loss of control: The central motif of the book is pushed to its extreme. Isabelle now faces the possibility that her unconscious self can perform deliberate actions—even harming her child.
Surveillance and truth: The night-vision camera is supposed to reveal objective reality, but it only deepens Isabelle's confusion. The video becomes a weapon of self-doubt.
The closed door: Waylon locking his door is a reversal of the earlier motif of open windows and unlocked entries. Now it is not the outside world that threatens, but the person inside the house.
Maternal fear: Isabelle's mother was afraid of her; now Waylon appears to share that fear. This parallel reinforces the cycle of distrust within families.

Why This Chapter Matters

This chapter is the breaking point of Isabelle's investigation. She has spent the story searching for an external culprit, but the nursery video forces her to look inward. It undercuts every assumption she held about her own innocence and makes the reader question whether she is a reliable narrator—or if she has been blocking a horrific truth. The chapter also deepens the tension between Isabelle and Waylon by introducing a new layer of secrecy (the conversation with Dozier) and by showing Waylon taking protective measures. It sets up the final act where Isabelle must confront what she may have done on the night Mason disappeared.

Study Questions and Answers

Why does Isabelle slam the laptop shut without watching the rest of the video?
She is too terrified to see whether her sleepwalking self carried Mason out of the nursery or harmed him. The act of closing the laptop mirrors her long-time avoidance of the painful truth.
What does Waylon's decision to lock his bedroom door suggest about his state of mind?
It implies that he no longer fully trusts Isabelle. He may fear her sleepwalking behavior or believe she is hiding something dangerous. The gesture also echoes her mother's past fear, deepening Isabelle's isolation.
How does the nursery video contradict Isabelle's earlier belief about her sleepwalking?
She had insisted that in the videos she never got closer than mid-room and never touched Mason. Now the footage shows her leaning into the crib and lifting him up, proving that her unconscious self can perform actions she would never consciously do.