The streets of Rosewood are festive and little kids are running around the streets hoping for a good year of trick or treats and five best friends are looking forward to the biggest party of the season. It is the Halloween before Alison went missing and the only concern for Aria, Emily, Hanna and Spencer is to score an invite to Noel Khan's Halloween party. But with a new girl in town to challenge Ali for Queen Bee dominance, Spencer possibly losing the class president election along with her parents' approval, and a shocking revelation for Aria about her father - there may be more to worry about than finding the perfect costume. With all of the tricks and treats floating around Rosewood, there may be something more sinister waiting out there for Ali and her best friends.