On her eighteenth birthday, Cleo receives a mysterious invitation to a scavenger hunt. She's sure her best friend Hope or her brother Connor is behind it, but no one confesses. And as Cleo and Hope embark on the hunt, the seemingly random locations and clues begin to feel familiar. In fact, all of the clues seem to be about Cleo's dead boyfriend, Declan, who drowned on a group rafting trip exactly a year ago. A bracelet she bought him. A song he loved. A photo of the rafting group, taken just before Declan drowned. And then the phone calls start, Declan's voice taunting Cleo with a cryptic question: You ready?