Chapter 3: Heuristics Traps Galore — How Cognitive Biases Shape the Investigation

⚠️ 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

The chapter opens with Mia, still recovering from her ankle injury, lying outside in the late-morning sun. She hears footsteps on the driveway and immediately assumes her father has returned with Eugene. This assumption, rooted in what she later identifies as selective perception—a confirmation bias that makes us interpret ambiguous events to match our expectations—sets off a chain of costly delays. Mia falls asleep and wakes at 1:30 to raindrops and a gust of wind. She texts her mother that Dad and Eugene are home, even though she never actually saw them.

When Mom and John return at 3:30, they find Dad missing. Mia checks his phone location and discovers it last pinged at 11:12 on the waterfall trail. She initially insists Dad must have lost his phone and gone back to find it, but the truth slowly emerges: she never saw Dad at all. The footsteps she heard were from a package delivery at 11:47, not from her father.

The family decides to search for Dad themselves, deliberately avoiding the police to protect Eugene, who is nonverbal and easily overwhelmed by strangers. They begin their search at 4:04—nearly four hours after they could have started if Mia had verified her assumption. Mia stays home to call hospitals while John bikes the park and Mom drives the perimeter. At 6:03, Mom calls to say they can't find Dad anywhere and that they need to call the police.

In that moment, Mia notices dark red crescents under Eugene's fingernails and a bloodstain on his shirt. Acting on instinct, she washes the clothes and makes Eugene shower before the police arrive, effectively destroying potential evidence.

Key Events

Mia hears footsteps and assumes Dad is home, but it's actually a delivery person.
She falls asleep and wakes to rain, texting Mom that Dad and Eugene are safe.
Mom and John return at 3:30 to find Dad missing; his phone last pinged at 11:12 on the waterfall trail.
Mia realizes she never saw Dad, only heard the delivery at 11:47.
The family decides to search themselves, avoiding police to protect Eugene.
They start searching at 4:04; Mia calls eleven hospitals.
At 6:03, Mom reports they can't find Dad and they need to call police.
Mia discovers blood under Eugene's fingernails and on his shirt, then washes the clothes and makes Eugene shower.

Character Development

Mia: The chapter reveals Mia's deep-seated cognitive biases—selective perception and anchoring—that lead her to misinterpret events. She also shows a protective, almost maternal instinct toward Eugene, prioritizing his comfort over the investigation. Her denial of Dad's disappearance is both a coping mechanism and a source of guilt.
John: He emerges as the most rational and worried of the siblings, immediately suggesting they call the police. His concern contrasts with Mia's dismissal, and his persistence highlights the family's collective denial.
Mom: She remains calm and pragmatic, trying to gather facts and manage the situation. Her decision to delay calling the police reflects her desire to protect Eugene, but also her own reluctance to confront the seriousness of the situation.
Eugene: Though nonverbal, his behavior—jumping, refusing to change clothes, hiding in the closet—signals his distress. The blood on his hands and shirt hints at his possible involvement in Dad's disappearance, though the chapter leaves this ambiguous.

Themes, Symbols, or Motifs

Cognitive Biases and Heuristics: The chapter's title, Heuristics Traps Galore, directly references the psychological concepts that drive Mia's mistakes. Selective perception and anchoring bias are not just academic ideas; they shape the family's entire response to Dad's absence.
Denial and Wishful Thinking: The family's decision to search themselves rather than call the police is rooted in a desire to keep the situation from becoming