After the jaw-dropping finale of "Pretty Little Liars" season 6, series creator I. Marlene King reveals that the "scariest" villain will cause further damage in Rosewood when the series returns for season 7.

During Tuesday night's finale, viewers of the show discovered that the Liars' newest nemesis, "AD," is Mary Drake, the secret twin of Alison's (Sasha Pieterse) mother.

It was also revealed that Mary was the real mother of Charles/Charlotte (Vanessa Ray), Ali's supposedly older sibling. But she was not working alone, since Ali's husband Dr. Elliott Rollins (Huw Collins) was also behind the latest series of terrors haunting the Liars to avenge Charlotte's death.

But according to the series creator, the explosive events in the season 6 finale will just be the "beginning of the end of PLL as we know it."

In an interview with The Hollywood Reporter, King mentioned that actress Andrea Parker will play an important part in the show even after her first character Jessica DiLaurentis died. According to Deadline, Freeform already promoted Parker to become a series regular when the show returns for season 7.

But fans would like to know when Alison will finally realize that her mother has a twin, since she was made to believe that she was hallucinating about her mother and Detective Wilden (Bryce Johnson) during the final episode. According to King, the answer will be revealed in season 7.

"That's all part of the story moving forward. When we come back this summer, you're going to find out a lot of answers," the series creator shared with Variety. "Season 7 is really the fastest-moving season we've ever had. It moves even quicker than Seasons 1 and 2, and you're going to get answers almost on an episode-by-episode basis. So you're going to get that answer really soon."

Aside from the dangers coming for the Liars, fans of the show are very excited to find out about the status of the romances between the Liars and their old lovers when the series returns next season.