Nancy and her friends must try to figure out why a girl is acting strangely after visiting a haunted house in this sixteenth book of the Nancy Drew Diaries, a fresh approach to the classic mystery series. Nancy's classmate, Willa, needs her help. Willa is convinced something is terribly wrong with her friend Izzy, but everyone has dismissed Willa's concerns, saying it's just teen angst. But Willa thinks it's more than that; she thinks Izzy is possessed...