Pretty Little Liars: Books 1 To 4 is a set of four young-adult novels by Sara Shepard. The story starts with the suspicious murder of a girl, after which the other four girls in her gang start getting into trouble caused by an unseen person.
Four girls named Spencer, Hanna, Aria and Emily were living a normal life, when one of their friends disappeared. Three years later, terrifying events start unfolding in the town of Rosewood, Pennsylvania which will change their lives forever. The girl who went missing connects the four in this thrilling read.
The hidden secrets, mysterious messages, murders and chilling events form the prime themes of the book. This was published by HarperTeen in 2009 in paperback.