Someone's life will change drastically in the season finale of "Pretty Little Liars" season 6, showrunner Marlene King revealed.

In an Instagram post, King warned that one of the Liars will lose her sanity in episode 20, titled "Hush, Hush, Sweet Liars."

According to the synopsis for the episode, Hanna (Ashley Benson), Emily (Shay Mitchell), Aria (Lucy Hale), and Spencer (Troian Bellisario) will have to outwit the new Uber Bad by sacrificing one of them as a bait. It also mentioned that Alison (Sasha Pieterse) will have strange visions during the season finale.

In a Twitter post, King told a fan that a huge twist will be revealed that will change Ali's life forever. Some speculations claim that the twist will have something to do with the twin theory that King finally confirmed this season.

If this turned out to be true, fans of the show are guessing that Alison's mother Jessica DiLaurentis (Andrea Parker) might have a twin. Other speculations claim that Ali herself could have a secret twin that she never knew existed.

Meanwhile, some speculations claim that the big twist in Ali's life could be instigated by her new husband Elliott Rollins, portray by British actor Huw Collins. Some believe that the charming doctor could be too good to be true.

In an interview with Wetpaint, Collins revealed that his character will have a significant role in the finale. "As to how much or in what capacity, you'll have to wait and find out," Collins said.

The actor also mentioned that the upcoming finale will make fans happy since it will give a lot of significant answers to the big questions in the series. "I would say that it's a gratifying finale," Collins revealed.

The final episode of "Pretty Little Liars" season 6 will air on Tuesday, March 15, but Freeform already announced that the seventh season of the series will premiere later this year.