Pretty Little Liars is a series of young adult novels by Sara Shepard. The series follows the lives of four girls—Spencer, Hanna, Aria, and Emily—whose clique falls apart after the disappearance of their leader, Alison. A year later, they begin receiving various messages from someone using the name "A" who threatens to expose their secrets. Originally developed as a television series by book packaging company Alloy Entertainment, the idea was described as "Desperate Housewives for teens". Alloy met author Shepard and gave her the property to develop into a book series. The first novel, Pretty Little Liars, was released in October 2006. It was followed by Flawless and Perfect in March and August 2007, Unbelievable and Wicked in May and November 2008, Killer in June 2009, and Heartless in January 2010. Wanted, announced as the eighth and final installment, was released on June 8, 2010. In December 2010 Shepard announced that she would write four more novels in the series, beginning with Twisted, to be released on July 5, 2011. - Source: Wikipedia
