I actually finished this book last week but forgot to post. Oops.
|Aria, Hanna, Emily and Spencer are shocked to learn of the existence of Alison's twin sister, Courtney, when she's introduced at a press conference. Courtney had spent her life in institutions due to "health issues" and her existence was kept secret by her family. It is revealed that Jason was not a patient at the Radley but instead he was visiting Courtney. She was finally released and went home to Rosewood, where she attempts to resume her sister's life and begins tentative friendships with Ali's old friends. She later reveals that she's actually Ali, the real Courtney had pretended to be her on the night of Ali's disappearance, and she was the one who was killed. When she had tried to tell her family who she was, they didn't believe her because Courtney was notorious for pretending to be Ali, and sent her back to the institution in Courtney's place. The girls are thrilled that Ali is back, and jump at the chance to go with her to the family's house in the Poconos after a school dance. On the way there, Spencer gets a frantic call from her mother telling her that Melissa has disappeared. Spencer had begun to believe that her sister was the one who killed Ali and that she may be after the rest of them, but once they arrive at the house it's revealed that Ali is the killer. They discover that the girl they were friends with years ago was actually Courtney, and the real Ali was stuck in an institution. She had killed Courtney for ruining her life, attempted to kill the girls in the forest fire, tried to have them arrested, and is now going to kill them by setting the house on fire.|
They're able to escape after stumbling onto Ian's body hidden in a closet and releasing a bound Melissa, who Ali had kidnapped and was planning to kill as well. Ali is trapped inside the house and it's assumed she died in the fire, although her body is never found.
After learning that her ex-husband shipped Hanna off to a mental institution, Ashley Marin transfers back to Rosewood and kicks Hanna's father, Isabel and Kate out of the house, thrilling Hanna. Hanna and Mike get back together.
Meredith goes into labor, giving birth to a girl named Lola. Aria and Noel get back together after it's revealed that Ali kissed him, not the other way around, and Ella breaks up with Xavier after learning of his inappropriate behavior towards Aria.
Spencer's father proclaims that even though he and her mother may not get back together, things are going to change for the better in their family, and Spencer and Melissa grow closer after almost being killed.
Emily buries everything she can find that reminds her of Ali at Courtney's grave, hoping she can finally find closure, but is unsure of whether the noises she hears at the cemetery are real or imagined. And somewhere, a new girl starts her senior year at an anonymous school, a girl whose name just so happens to be an anagram of Alison DiLaurentis. The reader is left wondering if Alison is...alive?