When they accidentally swap smartphones at an airport, Isabelle Wilcox and Matthew Rose are total strangers. By the time they realize what’s happened, they’re on France, and have begun to learn rather more about each other. Mild curiosity turns to obsession as their mobiles reveal secrets from their past lives. Having never met properly, they begin to feel intimately acquainted and, as their lives draw closer, events and feelings begin to race out of control.