Sara Shepard 
Pretty Little Liars #16: Vicious 

#1 New York Times bestselling series The explosive conclusion to the #1 New York Times bestselling series that inspired the hit ABC Family TV show Pretty Little Liars.High school seniors Aria, Emily, Hanna, and Spencer have been through a lot since their best friend, Alison Di Laurentis, disappeared five summers ago. A stalker named "A" has harassed them for their past mistakes and revealed their darkest secrets to the world. They’ve been on TV, hounded by the press, kicked out of school, arrested, and even put in jail. With time running out, and their lives on the line, one of the Liars does something so terrifying and shocking, fans will be left breathless.Full of unexpected twists and shocking revelations, Vicious is the jaw-dropping final installment in New York Times bestselling author Sara Shepards compelling Pretty Little Liars series.