The Insider.com

Pretty Little Liars flashed back -- way back -- to The First Secret in last night's Halloween one-off episode and revealed that Alison was actually the original recipient of a threatening text from A!

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But the revelations flew fast and furious as we learned why Alison hated Jenna so much, that Jenna was smokin' hot pre-blinding, how Mona fits into the picture, when Aria first met Ezra (loved this!) and that little Lucas might not be as innocent as we all assumed.

In fact, there were so many reveals on display you might have missed the most important ones, according to actress Sasha Pieterse. "Last night was the first time you saw Alison's room and I have to tell you, there's a lot of very telling things in there," she revealed to TheInsider.com. "You should have taken notes on everything that happens; you really need to watch the episode more than once, but especially the scene in Alison's room."

That's why I've taken the liberty of breaking down every inch of her bedroom -- but, before we get there, I had one more question for Sasha: is Alison really dead?

Yes, I know the police found "her body," but let's be real: the mid-season finale saw Alison create another metaphorical footprint in Rosewood when she "pulled" Emily out of the gassed garage. So what does Sasha think about her character's D.O.A. status?

"I'm kind of in between. She left lipstick on the cup in Hanna's hospital room and might have gotten Emily out of the garage, so I don't know. Then again, they were both so heavily medicated or out of it that you never know what they did [laughs]. It's cool that we're left guessing."

But it sounds like all those guesses will get answers when PLL returns in 2012! "The second half of the season answers a lot. A lot. Three more big questions come out of that, but the second half of the season is meant to satisfy the viewers. But at the same time, it brings a higher level of suspense. I don't think the girls know how dangerous things truly are."

Anyone else have a case of the tingles? OK, back to the matter at hand: Alison's boudoir! "This episode has so much thrown into it -- we've hidden so much in there," Sasha says. "The more you can find, the better for you!" Click here to get a closer look!