"Pretty Little Liars" follows four teenage girls in the fictional town of Rosewood, Pennsylvania, whose tight-knit group falls apart after their leader, Alison DiLaurentis, goes missing. One year later, the girls begin receiving cryptic and threatening messages from an anonymous figure named "A", who knows their deepest secrets, including those they thought only Alison knew. "A" uses this knowledge to terrorize the girls, forcing them to confront their past and work together to uncover the truth about their missing friend and the identity of "A".