Pretty Little Liars is an American teen drama television series loosely based on the book series of the same name. The show premiered in 2010 and tells the story of four girls whose lives are turned upside down after the disappearance of their friend Alison. They begin receiving mysterious text messages from someone signing as "-A" who seems to know their secrets. The show was a popular mystery that spanned 7 seasons until concluding in 2017.