Sadie Foust

Quick Facts

• Role: Primary protagonist and first-person narrator; the story’s central consciousness and mystery-driver
• Occupation/Age: 39-year-old emergency room physician, recently resigned from her Chicago hospital
• First Appearance: Arrives on a remote island off the coast of Maine after a family death
• Family: Married to Will Foust; mother to Otto and Tate; legal guardian/aunt to Imogen
• Premise: Moves into the late Alice Foust’s house and tries to restart family life in an isolated, suspicious community

Who They Are

Sadie Foust is a healer whose clinical calm collides with a life spiraling out of control. She’s a doctor trained to triage crises, yet her new world is defined by missing time, broken trust, and a murder next door—her neighbor Morgan Baines. As the family’s relocation exposes fractures in her marriage and unleashes old wounds, Sadie’s most formidable antagonist becomes her own mind: a patchwork of doubt, blackout gaps, and a growing certainty that danger isn’t just outside the house—it’s inside it.

Personality & Traits

At once capable and frayed, Sadie’s personality is a study in contrasts: a seasoned clinician who reads bodies for a living, and an unreliable witness to her own life. Her training gives her poise in emergencies, but her private world—strained marriage, hostile teenage ward, violent neighborhood drama—keeps her in a state of hypervigilance.

• Anxious but vigilant: Her inner monologue spirals with worst-case scenarios, yet that anxiety sharpens her suspicion when stories don’t add up, priming her to investigate rather than submit.
• Perceptive, yet destabilized by doubt: She senses something is wrong with the house and town from day one; still, she second-guesses herself, worn down by marital minimization and memory gaps that feed Unreliable Perception and Memory.
• Professionally detached: Years in emergency medicine teach triage over tenderness; in domestic conflicts, this reads as coldness and makes intimacy—especially with Will—feel clinical and strained.
• Protective mother: Her fiercest instinct is to shield Otto and seven-year-old Tate; guilt over past failures with Otto fuels her vigilance and fear in the new town.
• Fragmented memory: Blackouts and missing hours later cohere into a diagnosis of DID, making Sadie both a classic unreliable narrator and the novel’s most endangered witness.
• Worn-down exterior: Brown hair growing back after an impulsive cut; tired, crow’s-footed eyes; a trim build that registers as almost slight next to Imogen’s height—her body quietly records what her mind can’t say.

Character Journey

Sadie begins as a woman in retreat—fleeing Chicago scandals, a partner’s betrayal, and professional fallout—only to land on a remote island where isolation magnifies every fear. The murder of Morgan intensifies a domestic atmosphere of gaslighting and “coincidences”: threatening messages, bloody traces in her laundry, a missing kitchen knife. As her blackouts multiply, she leans on her diagnostic instincts, treating her life like a case file—cross-checking alibis, inspecting timelines, and interrogating the gaps. The revelation that her psyche contains an alter and that Will has been orchestrating her confusion reframes the entire mystery as engineered Deception and Manipulation. In the final confrontation, she refuses the script of passivity, kills Will to save herself and Imogen, and—one year later—chooses recovery and steadiness, moving deliberately through the lingering Trauma and Its Lasting Effects rather than letting it define her.

Key Relationships

• Will Foust: What looks like a marriage straining under a past affair is revealed as a system of control. Will exploits Sadie’s blackouts and distorts reality, a pattern of calculated Gaslighting and Psychological Abuse that weaponizes her mental health to cover his crimes.
• Imogen: Their bond begins in mutual suspicion—Sadie intimidated by Imogen’s guardedness, Imogen hostile to an interloper in her mother’s house. The truth of their shared losses and Imogen’s pivotal action in the climax transform them into allies, bound by survival rather than sentimentality.
• Otto Foust: Sadie’s guilt over failing to protect Otto from past bullying shapes her every decision; she monitors him for signs of renewed targeting and tries to give him the steadiness she lacks. Their quiet empathy—two anxious people reading rooms too closely—becomes one of the story’s most tender threads.
• Morgan Baines: At first, Morgan is a jealous thorn in Sadie’s side because of her friendly rapport with Will; after the murder, Morgan becomes a problem to solve. Discovering that Morgan is the sister of Will’s deceased fiancée, Erin Sabine, snaps the case into focus and exposes the lethal reach of Will’s past.
• Camille: Sadie’s alter (Camille) personifies the aggression and impulsivity Sadie has disowned. Will’s manipulation of Camille to further his violence makes clear that the real danger isn’t Sadie’s diagnosis—it’s the predator exploiting it.

Defining Moments

Moments that mark Sadie’s descent into danger and her climb out of it:

• “Die” scraped in frost on her car
  • Why it matters: Converts ambient unease into a direct threat, validating her anxiety and signaling that the island isn’t a refuge—it’s a trap.
• The bloody washcloth and missing boning knife
  • Why it matters: Physical evidence that violence has breached the home; undermines the narrative that she’s simply “overreacting.”
• Imogen’s cemetery confession
  • Why it matters: Their antagonism gives way to stark intimacy; both girls-turned-women carry a mother’s death, which welds them together before the finale.
• The final confrontation with Will
  • Why it matters: Will’s confession exposes the architecture of his control; Sadie killing him in self-defense is the moment she rejects victimhood and reclaims authorship of her story.

Essential Quotes

On the surface, there’s nothing not to like. But I know better than to take things at face value.

• Sadie’s default skepticism—part physician’s training, part trauma response—becomes her survival tool. The line frames the novel’s obsession with appearances and primes readers to question every “normal” detail of island life.

It’s been months now since the affair, and yet his hands are still like sandpaper when he touches me and, as he does, I can’t help but wonder where those hands have been before they were on me.

• The tactile disgust shows how betrayal lingers in the body, not just the mind. It also foreshadows the revelation that Will’s hands are connected to far worse than infidelity.

I didn’t overlook the warning signs because there were none to overlook.

• A self-defense against victim-blaming, this line captures the stealth of psychological abuse. It reframes Sadie’s “missed” clues as engineered invisibility rather than naiveté.

I am in the business of saving lives, not taking them. But there are exceptions to every rule. “You don’t deserve to live,” I say, feeling empowered because there’s no tremor, no shaking in my voice as I say it. My voice is as still as death.

• Sadie’s moral calculus pivots under duress; the physician who protects life chooses lethal force to stop ongoing harm. The steadiness of her voice marks the moment she steps into agency.

If time can turn something so undesired into something so loved, the same can happen to all of us. The same can happen to me. It’s happening already.

• A quiet epilogue to terror, this line reframes recovery as gradual reattachment—to place, to family, to herself. Healing isn’t forgetting; it’s learning to live with what remains.