Former best friends Hanna, Aria, Spencer, and Emily, who lost their best friend and leader, Alison, years ago when she disappeared, find themselves in grave danger when they pursue the truth about Alison.

The stalker's identity has finally been revealed, but Spencer, Emily, Hanna and Aria are bound to repeat the past, and continue to be bad.

After their missing friend's body is found and another of their friends commits suicide, four former best friends live in fear of their secrets being exposed by someone who is stalking them via their cell phones.

"It's spring break, and the pretty little liars are trading in Rosewood for a cruise vacation. They want nothing more than to sail into the tropical sunset and leave their troubles behind for one blissful week. But where Emily, Aria, Spencer, and Hanna go, A goes, too. From scuba diving to tanning on the upper deck, A is there, soaking up all their new secrets. Emily is smooching a stowaway. Aria's treasure-hunting partner is a little too interested...

"Emily's been shipped off to Iowa to live with her überconservative cousins. Aria's boyfriend is behind bars--because of her. Spencer's afraid she was involved in Ali's murder. But Hanna's fate is far worse: she's clinging to life in the hospital because she knew too much. If these girls don't start listening to me, Hanna's going to look like the lucky one"--P. [4] of cover.

Hanna, Spencer, Emily and Aria are trying to move on and forget about their old friend Alison DiLaurentis and all the torture she put them through, but someone is trying to keep her spirit alive.

"It's springtime in Rosewood, but while everyone else is searching for the perfect prom dress, Hanna, Spencer, Emily, and Aria are on a different kind of hunt: They're looking for A...Hanna puts her campaign for prom queen on the back burner to volunteer at a burn clinic, where one of A's victims is recovering. Emily digs into Ali's past at the mental hospital with some very crazy consequences. Spencer contacts an amateur private eye to help her stalk...

Spencer, Hanna, Emily, and Aria are forced to watch as all their secrets finally come to light, from their littlest lies to their darkest deeds. Now, one by one, the girls' worlds come crashing down around them. Spencer gets kicked out of Princeton. Hanna gets kicked out of her dad's campaign--and his heart. Emily gets kicked to the curb. And Aria may get kicked out of the country. Thanks to me, these girls have lost everything--except their lives,...