After a night out of partying and left behind by her friends, Ava wakes up and sneaks back home only to find that she's already safe in bed. But that's not Ava - it's someone who looks just like her. A time-traveling fugitive from the future has jumped back in time and stolen the teenager's body, her identity, and her life. What's more - she's not alone. There are others, hiding in the past, secretly living among us, plotting to alter the future. Without her body, Ava is a virtual ghost, silent and invisible to the world. And, so far as she knows, she's the only one who can stop them and put the timeline back on course.