Mona is clearly up to something, don't you think? This is a photo from the Pretty Little Liars episode "Thrown for a Ride."
Added:
The Pretty Little Liars sit around at school and discuss their next move in this scene from Season 5 Episode 4, "Thrown for a Ride."
Added:

Pretty Little Liars Season 5 Episode 4 Quotes

People come and go so quickly around here. Shana gone, Ali back. One girl checks out and another one checks in.

Mona

Hanna, you're not spontaneous. You make a Pinterest board before you change your nail polish.

Aria