After enduring Dr. Hortense Gray's experimental therapy on an island off the coast of California at a compound known as The Purgatorium, seventeen-year-old Daphne is delighted to learn she will now have a chance to have revenge on her parents and boyfriend by participating in their therapy. It's payback time, and Daphne can't wait to begin.Dr. Gray defends her dubious methods by claiming that all treatments come with risks, but when real bullets fly and lives are at stake, Daphne decides she wants no part of it and hatches a plan to save her family.