The next chapter of Pretty Little Liars [1] is finally just about here, and it looks like it's going to be one hell of a season. With tons of familiar faces returning [2] and a flood of exciting new details [3], it's clear we're going deeper into this Rosewood mystery than we ever have before. This, of course, leads to the biggest mystery of all: who is "A.D.," [4] aka "Uber A," and what is their endgame? We recently visited the show's set to chat with all the star players, and here's what they had to say about the most terrifying villain yet.

I. Marlene King (Creator)

• "Who is 'Uber A'? We’ve been calling this [person] 'A.D.,' but in this premiere, Spencer says out loud that this self-taught 'A.D.' is 'Uber A.'"
• "'Uber A' was born as 'A.D.' after Charlotte's death."

Janel Parrish (Mona Vanderwaal)

• "The final, most dangerous, craziest 'A,' and there's nothing that this 'A' wouldn't do to get their way."
• "Obviously 'Uber A' doesn't miss a thing . . . so 'Uber A' knows that there is something they're trying to cover up and is going to use it to play that final game."
• "I actually don't even know who 'Uber A' is yet, so I'm excited for that. I think just to find out why. Why this 'Uber A' has been playing this game. If that was their intention from the very beginning. If Mona, as the first 'A,' knew 'Uber A.'"

Shay Mitchell (Emily Fields)

• "Not one to mess with. Yeah. That's basically it. The uber-est of all."

Ashley Benson (Hanna Marin)

• "Hanna is abducted by 'A.' She's being tortured and abused in all kinds of ways, and they're just trying to save her. . . . You'll see a shadowy figure. But you won't actually see who it is."
• "Mary Drake and Elliot tie into Charlotte and her murder. They could be on the 'A' team. I'm not sure. But, as of now I think that they are a team and they could be teaming up with 'A' eventually."

Lucy Hale (Aria Montgomery)

• "Some old faces are coming back. But I can't say exactly who. I'd like to bet they have some sort of involvement."