Perfect

Perfect is the third book in the series Pretty Little Liars by Sara Shepard, which was published on August 21st, 2007 by HarperTeen.

Book Summary
Aria tries to keep her father Byron's affair a secret from her mother and brother, while Hanna deals with her social downturn by resuming her bulimia. Emily is in a secret romantic relationship with Maya. Spencer remembers pushing Ali into a stone wall after a heated argument, and fears that she is the one who killed her. After Aria ignores "A's" threats, "A" reveals her father Byron's affair to Ella, who kicks Aria out of the house. "A" also reveals Emily and Maya's relationship publicly, and Emily's parents force her into a program to "cure" her apparent homosexuality. Aria is also cheating on her boyfriend with her AP English teacher Ezra; "A" sends a picture of them kissing to Aria's boyfriend, who calls the police. Hanna is humiliated at Mona's 17th birthday party, and later receives a text from "A." This time, the number is not a jumbled mess, and Hanna recognizes it: she knows who "A" is. She calls Spencer, Emily, and Aria to meet her at their special spot, the Rosewood school playground; before she can tell them what she knows, Hanna is hit by an SUV.

Messages from "A"
She knew too much ( an txt after Hanna's accident) You really thought I was gone? Puh - leash. I 've had been watch this whole time. In fact I might be watching you right now. And girls if you tell ANYONE about me you be sorry