Bree Bennis finally has it all—a non-comatose mother, an uber-hot (albeit anachronistic) boyfriend named Finn, and a newfound mission to protect the timeline from those who would skew it for their own gain. But when she leans over one day to smooch said boyfriend, her lips meet those of her arch-nemesis Wyck instead. The timeline has been altered, and Bree is caught in the crosshairs. But when she goes back to repair the damage, she is stopped by none other than her Future Self, who delivers an urgent message: Someone is kidnapping Shifters from the distant past. It's up to Bree to stop them. But first, she has to figure out who...and why.

To follow the trail of chronocrumbs, Bree reluctantly accepts her new undercover gig as Wyck's girlfriend. Everything goes spiffy until Finn shows up in the 23rd century on the eager arm of a gorgeous fellow Shifter. Blark. Even as Bree struggles with jealousy, she battles the nagging dread that Finn might be better off with someone less chronologically complicated. Her worst fear is confirmed when Finn becomes the kidnapper's next victim. As Bree zeroes in on the culprit, they unravel her life one timeline-change at a time. She realizes that she alone has the power to save herself and everyone she loves. But to do that, she may lose Finn forever.