While traveling down a desolate road, Maria comes upon an apparently abandoned school bus. A girl has written "HELP ME" in one of the windows and Maria quickly discovers the messy secrets that lie in the back of the bus. As the killer reappears, Maria finds herself now hidden and trapped as the killer takes them on the ride of their lives. Their journey leads to a bizarre location in the desert, where they'll quickly learn their enemy is not who they think. The girls must figure out whom to trust, if even each other, if they hope to return home, alive or dead.