Chapter 27 “Rob” — Summary, Analysis, and Key Themes

⚠️ 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

Chapter 27 opens with Rob running errands for Jack's unborn child. Jack refuses to see a doctor, insisting she'll give birth at Sundial. Rob drives to a mall off Route 40 and buys everything a newborn could need—clothes, diapers, formula, a mobile, a bath—filling Mia's truck to the windows.

On the way back, Rob stops at a pharmacy in Bone for prenatal vitamins. The pharmacist initially mistakes her for Jack, and Rob leans into the confusion, claiming her sister is visiting relatives in Nebraska. She pretends to be pregnant, telling the pharmacist she's due in December and that the baby is a girl. For a few minutes, Rob feels a profound sense of safety and joy—she imagines her lost daughter Callie alive again. But the illusion collapses as soon as she leaves, and Rob pulls over to weep, hating the return to her real self.

Back at Sundial, Rob watches the dogs in their pen. She counts them: ten heads, ten tails. Weren't there eleven yesterday? Mia enters Twenty-Three's pen alone, and the rottweiler suddenly attacks—not with aggression, but with fear. The dog seems to be fighting something invisible, yelping and howling at hallucinations only she can see. Jack grabs the tranquilizer gun from Rob, who is frozen, and shoots Twenty-Three three times.

Mia explains that the genetic modification called the click has failed in Twenty-Three. The editing mechanism has begun pasting the wrong material into the dog's genetic code, preventing her from processing fear correctly. Twenty-Three was experiencing a traumatic memory—perhaps of her own tail being maimed—and reacted in what she perceived as self-defense. Mia then reveals the worst: Twenty-Three killed Kelvin, an older dog, and began eating him while he was still alive.

Rob decides to shoot Twenty-Three herself, screwing a suppressor onto a .22 rifle. But Mia stops her, striking Rob and revealing the dog may be pregnant. Mia wants to see if the puppies inherit the defect.

What follows is the chapter's devastating core. Mia, Falcon, and Jack finally tell Rob the truth about her childhood. Rob and Jack were found as abused children kept in cages in a cellar. There were five cages; other children had been there before them. Their abusers—a man and a woman—were found dead: the man overdosed, the woman strangled with wire. Rob, it turns out, killed them both. She also stabbed Jack in the neck with a screwdriver, leaving the star-shaped scar Rob always assumed was unrelated to her.

Mia and Falcon, rather than surrendering the girls to the state, genetically modified them. They made a tiny edit to the MAOA-L gene—the so-called click—to suppress violent tendencies. The dogs at Sundial were a control group, a way to observe the long-term effects of the modification without drawing attention to their true purpose.

Jack reveals she has been deteriorating. The click is failing in her, just as it failed in Twenty-Three. She hallucinates, processes emotional memories incorrectly, and fears she may hurt people. She refuses to leave Sundial because the alteration may pass to her baby through germline editing.

Rob learns that Pawel—the man she believed was simply a drug dealer—was the first human subject. He was a Polish man who killed his entire family one Christmas, and the click gave him a lifetime of remorse. Jack used drugs to suppress her violent impulses, a trick Pawel discovered.

Rob calls Asia, who is furious about the stolen car. Asia found a pregnancy test in Rob's drawer, and Rob confirms she is pregnant. But the call ends in despair—no one can help her now.

The chapter closes with Jack's chilling question. Rob has been hitting people, trying to shoot dogs, acting out of character. Jack asks: are you a bad dog, too?

Key Events

Rob buys baby supplies and pretends to be pregnant at a pharmacy, briefly feeling Callie's presence again.
Rob notices the dog count has dropped from eleven to ten.
Twenty-Three attacks Mia, hallucinating; Jack tranquilizes the dog.
Mia reveals the click has failed in Twenty-Three, causing psychosis-like symptoms.
Mia discloses that Twenty-Three killed and began eating Kelvin.
Rob attempts to shoot Twenty-Three; Mia stops her, saying the dog may be pregnant.
Mia, Falcon, and Jack reveal that Rob and Jack were caged, abused children who were genetically modified.
Rob learns she killed her abusers and stabbed Jack.
The dogs are revealed as a control group for the human experiments.
Jack admits the click is failing in her; she fears harming others and passing the defect to her baby.
Rob learns Pawel was the first human subject, a Polish man who murdered his family.
Rob calls Asia and confirms her pregnancy.
Jack suggests Rob may also be deteriorating.

Character Development

Rob undergoes the most radical shift in this chapter. Her sense of self—built on being the good one, the stable sister—collapses when she learns she killed her abusers as a child. The revelation forces her to confront that her identity was partly manufactured by genetic intervention. Her brief fantasy of pregnancy shows her deep, unhealed grief for Callie, and her violent impulses (shooting Twenty-Three, slapping Jack) suggest the click may be failing in her too.

Jack emerges as the tragic center of the chapter. She has known the truth for years and has been silently deteriorating, using drugs to suppress violent urges. Her refusal to leave Sundial—despite Rob's pleas—is framed as sacrifice: she fears what she might do to others and what she might pass to her child. Her line about being the bad dog carries both self-loathing and acceptance.

Mia is revealed as a deeply compromised figure. She claims love and penance, insisting she gave her youth to the girls. But Rob's accusation—that Mia and Falcon scouted for them like stray dogs—exposes the uncomfortable truth: love and exploitation are not mutually exclusive. Mia's trembling, her desperate need for Rob to understand, suggests genuine guilt, but the chapter refuses to absolve her.

Falcon is shown as disturbingly sincere. He believes the experiments were acts of love, and his lack of guilt is more chilling than any villainy.

Themes, Symbols, or Motifs

The click operates as the novel's central symbol: tiny scissors snipping away at identity, memory, and emotion. The chapter literalizes this with Jack miming scissors with her fingers, clicking her tongue with each imaginary snip. The click is both salvation and curse—it saved the girls from their violent natures, but it is now eating Jack from within.

The good dog/bad dog dichotomy structures the sisters' self-understanding. Rob believed she was the good one; Jack accepted the role of the bad one. The chapter dismantles this binary, showing that both were modified, both are deteriorating, and both are, in some sense, dogs trained by their keepers.

Cages and confinement recur throughout. The childhood cages in the cellar are mirrored by the dog pens at Sundial, by Jack's self-imprisonment, and by Rob's growing sense that she cannot leave. Sundial itself becomes a cage disguised as a home.

Motherhood and loss are intertwined. Rob's false pregnancy is a desperate reenactment of her lost daughter; Jack's real pregnancy is a source of terror because of what it might inherit. The unborn child represents both hope and the perpetuation of trauma.

The desert functions as a witness. Rob notes that the desert knows who she is, suggesting that the landscape holds the truth she has been running from.

Why This Chapter Matters

Chapter 27 is the novel's revelation chapter—the moment when the central mystery of Rob and Jack's past is finally exposed. It reframes everything that came before: the dogs, the experiments, the sisters' relationship, and their isolation at Sundial. The chapter also raises the stakes for the remainder of the novel by suggesting that Rob herself may be losing control. The click, once a source of stability, is revealed as fragile and failing. The chapter transforms the novel from a mystery about the present into a tragedy about the past's inescapable grip.

Study Questions and Answers

1. Why does Rob pretend to be pregnant at the pharmacy, and what does this reveal about her psychological state?

Rob's deception is a form of grief. Pretending to be pregnant allows her to feel Callie's presence again—the warm, beating love she lost. The chapter explicitly states that the five minutes of pretending were the most wonderful she'd had in months, and that withdrawing from the illusion was terrible punishment. This reveals that Rob's identity is fractured by unresolved loss, and it foreshadows her later confession to Asia that she is actually pregnant. The scene also establishes Rob's capacity for deception, which becomes thematically important as the chapter unfolds.

2. How does the revelation about the dogs as a control group change the reader's understanding of Mia and Falcon's experiments?

The dogs were never the true subjects—they were a cover. Mia replicated outdated Langley experiments with remote-controlled brain stimulation to hide the fact that she and Falcon were observing the click's long-term effects on Rob and Jack. This reframes the entire novel's animal imagery: the dogs were stand-ins for the human subjects, and their suffering (Kelvin's death, the coyote puppy, the dogs who died of sepsis) was collateral damage in a human experiment. It also implicates Mia and Falcon more deeply, suggesting they viewed the sisters as research material as much as children.

3. What does Jack's refusal to leave Sundial reveal about her character and the novel's treatment of sacrifice?

Jack's refusal is framed as both self-protection and protection of others. She fears she may hurt people if the click fails completely, and she worries the genetic alteration may pass to her baby. Her choice to stay is a form of penance—she accepts the role of the bad dog to keep others safe. But the chapter complicates this sacrifice by showing that Jack has been deteriorating for years, hiding her condition from Rob. Her refusal is also a resignation: she no longer believes she deserves freedom. The novel suggests that sacrifice, when born of guilt and self-loathing, is not liberation but another form of imprisonment.