Dylan lives in a town called Pine Mountain that's currently undergoing conflict with "flatlanders" and "weekenders" who are taking over the economy and adding gated developments. That conflict underscores the problems when a new girl, Cate, starts in their school, and Dylan finds herself confiding her psychic ability. She's never told anyone except her mother and the town's deputy, not even her best friend, Pilar. Since Vrettos gives plenty of time for us to get to know Dylan and Pilar's friendship before Cate enters the story, the emotional impact is higher.
Dylan's first vision happens when she's five, and a boy in her kindergarten class is murdered. Clarence's murder dramatically influenced the town and her friends, so when another murder occurs, with evidence that it was the same "Drifter," Dylan begins to wonder if she could somehow prevent further killing, instead of just seeing where to locate the bodies.
Though the solution to the mystery isn't that surprising, it has a satisfying resonance.