Isabelle's Sleepwalking Investigation – Chapter 37 Summary

⚠️ 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 cancels her lunch with Waylon after receiving a callback from Dr. Harris. She drives to his office, lying to him about her sleep quality, routine, and medication compliance. She pivots the conversation to sleepwalking, claiming she might have started again after finding objects moved in her home. Her real purpose is to learn whether a sleepwalker can commit violent, even homicidal acts without memory of them. Dr. Harris confirms that homicidal sleepwalking is rare but possible, citing the case of Kenneth Parks. He warns that severe sleep deprivation is more dangerous and can lead to hallucinations and delusions. Isabelle promises to try to sleep, but the ease of her lies and her deep, unspoken fears suggest she is hiding something far darker.

Key Events

Isabelle receives a call from Dr. Harris and decides to cancel her lunch with Waylon to attend a therapy appointment.
During the session, Isabelle lies repeatedly about her sleep, exercise, alcohol use, and nighttime routine.
She steers the conversation to sleepwalking, fabricating a story about finding furniture moved.
Isabelle asks directly whether a sleepwalker can kill someone and not remember it.
Dr. Harris describes the 1987 Kenneth Parks case, in which Parks drove fourteen miles and killed his mother-in-law while sleepwalking, and was acquitted.
He explains that during sleepwalking, the moral reasoning part of the brain is asleep, so a person can do terrible things they would never do while awake.
Isabelle abruptly ends the session, but Dr. Harris warns that chronic sleep deprivation is more dangerous than sleepwalking, causing hallucinations and delusions.
She promises to get sleep, but the chapter underscores her growing unease and the lies she tells.

Character Development

Isabelle: Her mastery of deception deepens—she lies to Dr. Harris without hesitation, and her rehearsed story about sleepwalking reveals a calculated effort to extract information. Her visceral reaction to the Kenneth Parks case, and her internal reference to Mason's nursery and Margaret's warning, tie her childhood sleepwalking to a potential adult trauma. She is torn between seeking answers and concealing the truth.
Dr. Harris: Remains perceptive and concerned, pressing Isabelle about her well-being and ending with a pointed warning about sleep deprivation. His clinical detachment masks unease; he senses she is holding back.

Themes, Symbols, or Motifs

Sleepwalking as a metaphor for moral disconnection: The idea that the “moral teaching” part of the brain goes offline during sleepwalking echoes Isabelle's vague, troubling memories and her fear of having done something unforgivable.
Deception and self-protection: Isabelle lies to her therapist, the same professional she once trusted, to protect her secret. The lies flow “too easily,” highlighting how she has internalized hiding.
Memory and guilt: The chapter probes whether violent acts can be committed without conscious memory, aligning with Isabelle's fragmented recollections of the night Mason disappeared.
The danger of sleep deprivation: Dr. Harris's final warning links Isabelle's chronic lack of sleep to potential hallucinations, suggesting her grip on reality may be fraying.

Why This Chapter Matters

This is the first time Isabelle openly confronts the possibility that she could have harmed Mason during a sleepwalking episode. By researching homicidal sleepwalking, she reveals her deepest fear: that she is responsible for her son's disappearance without remembering it. The chapter also reinforces her pattern of lying to authority figures and sets up a critical tension between what she knows and what she is willing to admit.

Study Questions and Answers

1. Why does Isabelle fabricate the story about finding objects moved in her home? She needs a plausible excuse to ask Dr. Harris about violent sleepwalking without revealing her true concern—that she may have harmed Mason while asleep. The lie lets her obtain clinical information while maintaining her cover.

2. What is the significance of the Kenneth Parks case in this chapter? The case provides a real-world example of homicidal sleepwalking and acquittal, giving Isabelle (and the reader) a precedent for her fear. It shows that a person can commit extreme violence during sleep and have no memory of it, which directly mirrors her own anxious speculation about the night Mason vanished.

3. How does Dr. Harris's warning about sleep deprivation advance the plot? It introduces the possibility that Isabelle's fragmented perception, microsleeps, and potential hallucinations may be fueled by extreme exhaustion, not just sleepwalking. This clouds the reliability of her testimony and hints that her mind could be creating false memories or distorted recollections of the kidnapping.