Pretty Little Liars is an ABC Family drama-mystery television show which ran for seven seasons between 2010 and 2017. The show is loosely based off the book series of the same name by Sara Shepard. The show follows five girls, Spencer Hastings, Alison DiLaurentis, Aria Montgomery, Hanna Marin and Emily Fields, in the fictional town of Rosewood, Pennsylvania. After Alison goes missing, the clique falls apart. A year later, the group begins receiving threats from a mysterious person who signs their tweets ?A.? or ?A.D.? The girls first believe it?s Alison, but after Alison is found dead, it is revealed that ?A.? is somebody else.