he first season of Pretty Little Liars, based on the books of the same name by Sara Shepard, premiered on June 8, 2010 and concluded on March 21, 2011 on ABC Family. It tells the story of a clique of five girls - Spencer, Aria, Hanna, Emily, and Alison - until one of them goes missing, Alison. One year later, the girls have grown apart and start getting messages from a mysterious 'A', and thinking it's Alison, they soon find out that Alison is dead, and someone else is taking her persona. The show will follow the basic premise of the novels.

The show premiered to 2.47 million viewers, and retained a regular audience of 2.5 million viewers during its summer run. The summer finale scored 3.07 million viewers, achieving a series high. The show went on hiatus, and returned with its winter premiere on January 3, 2011, with 4.22 million viewers, becoming one of ABC Family's top telecasts ever.

Overview from themoviedb.org