When Lucy Hale, who stars as Aria Montgomery on Pretty Little Liars, chatted with Ryan Seacrest about the hit show, she shocked fans by openly admitting who the mysterious 'A' is!

But don't worry, in the clip below Lucy only reveals 'A's identity in the Pretty Little Liars book series that the show was based on — Lucy doesn't even know who's behind all the threatening messages on the show. Hopefully we'll get one step closer to unraveling the mystery on this week's brand-new episode "Please, Do Talk About Me When I'm Gone" airing Tuesday at 8 p.m. on ABC Family.

Who do you think 'A' is on the Pretty Little Liars show?