Pretty Little Liars: What Does "A.D." Have to Do With Mary Drake and Dr. Rollins?

In the season premiere, Spencer and Toby ransack Mary's lair at the Lost Woods Resort. They find a few random things — like a bunch of books in different languages and a passport filled with stamps — but a few notable finds have certainly piqued our interest. We can't ignore the fact that she has a book about being tech-savvy. Even more interesting, eagle-eyed viewers can spot a book about mastering the art mask making in the background.