“It’s impossible to know another person, isn’t it? To step past that locked door of their secretive inner self. . . . But honestly, do you even want to know?”

One sunny morning in June, Margaret Carpenter wakes up to find a new iPhone on her doorstep. She switches it on and is greeted by a text from her best friend, Charity Atwater. The problem is, Charity’s been missing for over a month. Most people in town – even the police – think she’s dead.

Margaret and Charity have been lifelong friends. They share everything, know the most intimate details about each other . . . except for the destructive secret hidden from them both. A secret that will trigger a chain of events ending in tragedy, bloodshed, and death. And now Charity wants Margaret to know her story – the real story.

In a narrative that takes place over one feverish day, Margaret follows a series of increasingly disquieting breadcrumbs as she forges deeper into the mystery of her best friend – a person she never truly knew at all. . . .