In a dark room of a dilapidated house, as a storm rages outside, Matthew lights a candle and places it in the center of the floor. Its light spreads across the wall and illuminates Sophie, tied up in a chair facing him. She is frightened, fearful of what he might do next. But for now, it seems, all Matthew wants to do is talk. Talk about the events of nearly twenty years ago, about their strange childhood, and about the summer when Sophie grew up and everything changed . . . forever.
Young Mattie and Sophie lived in a world seemingly without constraints. Their cold mother barely paid attention to her children. Their father, a mere shadow in their lives, was never home. So Mattie and Sophie had the run of the gardens and the woods beyond. They played youthful games, but Sophie was extraordinarily intelligent, a fact she took great pains to hide from her teachers, so as not to stand out. Sophie was everything to Mattie, and he worshiped her. He wanted to know her secrets, the things that went on inside her brilliant mind. But Sophie was changing. And the summer before she went away to boarding school, the things she had worked so hard to conceal would come spilling out—and Mattie would have to live with the shocking consequences.
Now he’s all grown up, too, and Matthew wants answers to the questions that still darken his mind—no matter what the cost. . . .
- Chekhov's Gun: The references to there being multiple candle stubs around the room foreshadows that Matthew has done this more than once.
- Collective Identity: "Sophie" itself. It's never made clear if Matthew blames "Sophie" for things he did (such as killing the real Sophie), and he forces the narrator to pretend to be "Sophie" herself.
- "Groundhog Day" Loop: Played with, in a notable version of this trope that doesn't involve any form of supernatural interference or time travel. By the end of the novel, Matthew has clearly forced multiple women to play this "game" of being Sophie over one night, and killed them all in turn, for unspecified reasons, and he's not going to stop. While the "Sophie" we've followed throughout the novel is already dead, dying, or at best, imprisoned in the bunker waiting to die, it seems inevitable that Matthew will force more women into repeating it for him.
- The Ending Changes Everything: Matthew is a serial killer and there are multiple Sophies that he kidnapped and murdered.
- Extremely Short Time Span: The "past" section covers years, while the present covers only a single night.
- It Was a Dark and Stormy Night: The present section of the novel takes place over a single one.
- Karma Houdini: Matthew gets away with everything he did, including serial murder, but it's at least somewhat downplayed as he seems like he'll be tormented forever.
- Locked Up and Left Behind: What Matthew does to all his victims, including the narrator, and may have done to his real sister Sophie, although it's unclear whether or not she wanted him to.
- Not the First Victim: This is the central plot twist that leads to The Ending Changes Everything. The first twist is that the present-day narrator isn't really Sophie - she's simply a woman that Matthew has kidnapped and forced to act as Sophie. The second twist is revealed when she sees the multiple candle stubs around the room and, later when she sees the gnarled corpses in the bomb shelter, that Matthew has killed multiple women through the same "game" over the years.
- One-Word Title: First name of Protagonist Title style.
- Protagonist Title: First name One-Word Title style.
- Sealed Room in the Middle of Nowhere: The house might count, but a clearer example is the bomb shelter in which Matthew imprisons the other Sophie.
- Tomato in the Mirror: Rather than finding out she's the one, Sophie discovers that she isn't the only "Sophie" to hear the story.
- Where I Was Born and Razed: Sophie burns down the house just after convincing her mother to commit suicide, and Matthew carries on the tradition by imprisoning women in his old house.