"Pretty Little Liars" Season 4, Episode 13 ("Grave New World") shocked viewers in its Halloween Special. Alison DiLaurentis (Sasha Pieterse) shows up un-dead. In interviews, Sasha and Troian Bellisario tease fans on what to expect, and what's ahead when PLL returns in January.

Spoiler alert: This feature contains spoilers from "Pretty Little Liars" Season 4, Episode 13, "Grave New World."

Alison DiLaurentis (Sasha Pieterse) reveals herself in “Pretty Little Liars” Season 4, Episode 13, “Grave New World.” (Credit: ABC Family on Tumblr.com)

The ABC Family series continues from its mid-season finale, "Now You See Me, Now You Don't." In this episode, it was revealed Alison is alive. All those times the girls thought there were hallucinating, they may have actually seen their friend around. Then came Halloween.

Toward the end of "Grave New World," Sasha Pieterse shows up in her red coat, prompting jaws to drop and eyes to widen. Reactions quickly flooded on Twitter.

(Credit: Twitter.com)

"There's a lot of different people that she saw the night she disappeared, a lot of different people that she came in contact with that the girls didn't know about, and you've yet to find out," Sasha Pieterse told Kristin dos Santos of E! Online.

Sasha goes on to say that more Ezra Fitz (Ian Harding) mysteries will be unfolded in the next Pretty Little Liars (2014) episodes. Apparently, there's a "big reason" why Ezra has been tracking down Alison.

When will 'Pretty Little Liars' return to ABC Family?

When the series returns in January 2014, PLL viewers hope to:

- unravel Ezra a bit more (some fans say Ezra is A, others think he's not likely to the Big A)
- answer with certainty whether Ezra Fitz has a twin
- find out whose body was found in the series pilot
- answer so many "whys" and "hows"

The Twitterverse was peppered with shocked reactions from fans after seeing the Halloween special of "Pretty Little Liars" Season 4. (Twitter.com)

Speaking to Wetpaint, Sasha notes Pretty Little Liars Season 4 is really tough on Ali, Spencer (Troian Bellisario), and Aria (Lucy Hale).

"There's a lot of sad things, happy things, angry things going on with (Ezra), and we know it will be a very intense season for him - and for my character, Spencer and Aria."
"You get to learn the most fun secret about Spencer, and that's: why wasn't she with the rest of the girls when they woke up and why was she awake to hear Alison scream," Troian Bellisario told Wetpaint.

Pretty Little Liars Season 4 returns on Jan. 7. This second half, popular known as "Season 4B," is making a lot of fans tense due to the last minutes of 'Grave New World.'

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