Content Warning: The source material and this guide contain descriptions of self-harm, suicidal ideation, and death by suicide.

The Prologue consists of emails between Dawn Schiff and Seth Hoffman. Dawn’s messages are highly formal, while Seth’s are brief and casual. Dawn requests an urgent appointment with Seth, and they agree to meet at 2:00 pm the next day.

Chapter 1 is told from the first-person perspective of 30-year-old Natalie Farrell. Natalie is the top salesperson at Vixed, a nutritional supplement company in New England. Arriving at the office, she notices that the cubicle of accountant Dawn Schiff is empty. Natalie is surprised at this because Dawn is always punctual and keeps to a rigid schedule. Natalie’s best friend, Kim Healey, is back from her honeymoon. Natalie unintentionally upsets Kim by incorrectly guessing that she is pregnant. When Natalie points out Dawn’s absence, Kim makes fun of their colleague, calling her “a weirdo.” She also references Dawn’s obsession with turtles. Natalie defends Dawn, reflecting that she has always intended to get to know her better.