The series follows the lives of four girls – Spencer Hastings, Hanna Marin, Aria Montgomery, and Emily Fields – whose clique falls apart after the disappearance of their leader, "Alison DiLaurentis". Three years later, when the girls are juniors in high school, Alison's body is found, and they begin receiving various messages from someone using the alias "A" who threatens to expose their secrets and get revenge.
