pretty little liars book one ending

Until one day when Spencer, Hannah, Aria and Emily suddenly got strange mysterious text messages from "A." They began to get more and more messages and then they got more freaky. The messages started to predict the future and "A" knows all, so nothing is hidden or safe.
After a while the girls started receiving less messages so they thought it was over. But the nightmare was just beginning. None of them knew that all of them had been getting the messages, they thought it was just them but once they knew they immediately thought it was Ali and that she hadn't died and everything was going to return to normal, but they were wrong. About a week after they made the prediction about Ali being "A" the police found her body in her backyard between two cement pieces.
"A" knows everything about these pretty little liars, and she's not afraid to tell.