Sara Shepard

After their friend Alison, missing for more than three years, turns up dead, four former best friends, each of whom had a secret known only by Alison, begin receiving frightening messages from someone identified by the letter "A."

The four former best friends try to overcome their friend Ali's murder, but become alarmed when they receive text messages from the mysterious "A" and learn that their friend's accused killer has been released from jail on bail.

Former best friends Emily, Aria, Hanna, and Spencer continue to live in fear as they struggle to keep hidden even more secrets and someone new begins stalking them via their cell phones.

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.

Seventeen-year-old Emma Paxton steps into the life of her long-lost twin Sutton to solve her murder, while Sutton looks on from her afterlife.

"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...

Aria, Emily, Hanna, and Spencer find their lives unraveling when A's plans change and the girls are taken to the police for questioning.

Unable to convince anyone that she was pushed before she was rescued from the bottom of a hotel pool, a rising author struggling with depression and memory loss begins to question her sanity as elements from her debut novel mix up with events in her real life.

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.

Now that troubled Thayer Vega is back in town, Emma Paxton must struggle to figure out the relationship her twin has with him...and whether he may have been the one to kill her.