Four friends work together to uncover the mystery of their best friend's murder. The TV series is loosely based on the book series of the same name by Sara Shepard.
The show won multiple People's Choice Awards. Its first season resulted in three 2010 Teen Choice Awards for Choice Summer TV Show, Choice Summer TV Star: Male (Ian Harding) and Choice Summer TV Star: Female (Lucy Hale). It inspired two spin-offs, Ravenswood and Pretty Little Liars: The Perfectionists.