Since You've Been Gone explores the story of Emily, a quiet teenager whose sociable and daring best friend, Sloane, has vanished, leaving behind nothing but a random list of bizarre tasks. Emily would never normally consider completing these tasks, but with the unexpected assistance from popular classmate Frank Porter, she decides to give them a try.

The summer that follows is one of self-discovery and adventure as Emily embarks on each task, hoping that they might somehow lead her to Sloane. What starts as an intimidating challenge becomes an exciting journey that pushes Emily out of her comfort zone and into a series of firsts that could change her life forever.