The Ecstasy of Isabel Mann.

Teenager Isabel Mann is seduced by a violent sect of day-walking vampires. Her classmates start to go missing, attracting two detectives.Things get weird as the disturbed teenager kills at will in the nearby woods. She's aided by head vampire Alejo, and eerily by Isabel's lost mother, an earlier recruit. She's trained in the art of the kill with horrifically bloody results for those she loves.