Credit: ABC Family

Now that we know Ezra really might be "A", it seems like we can't trust anyone to be a good guy on Pretty Little Liars. The show is so full of twists and turns that we never know what's coming next, which is why we like to dive into the world of awesome, crazy fan theories every week. After all, with this show you never know when the fans are going to get something totally right.

This week, we want to talk about the very plausible and fairly popular theory that Spencer (Troian Bellisario) may have done something less-than-savory to her former bestie the night Ali disappeared.

What makes anyone think Spencer has such a dark secret? There are a number of reasons, some of which this Tumblr user touches upon.

Spencer and Ali fought that night. We've already seen in flashbacks that Spencer and Ali had a falling out that night, and in this interview, Sasha Pieterse once again mentions that Spence and Ali weren't on good terms, which makes us think that's important.

Spencer has a secret. We know from spoilers that Spencer has another big secret that will be revealed in Season 4B, and it sounds like it involves the night Ali disappeared. Could it be that she hurt Ali? Troian Bellisario also teased that Spencer will have a "Patrick Bateman" moment. And if you don't know, Patrick is the very bloody protagonist of American Psycho.

She had the time. We know that Spencer was up and out of the barn before the other Liars. She claimed that she was looking for Ali, but that could have been a cover for what she actually did to her former BFF.

Her family has so many question marks. There's the thing with her dad burning the hockey stick. There's Melissa claiming to be protecting her baby sis. There's her mom working on Garrett's defense. The Hastings always seem to know more than they're letting on. Could they all be trying to shield Spencer from the consequences of a very bad thing she did?

Ali doesn't trust one of the Liars. We know from Grunwald that Ali doesn't know if she can trust the Liars. Maybe it's Spencer in particular she's worried about...

It happened in the books. The show has diverged widely from the Pretty Little Liars book series at this point, so this doesn't necessarily mean anything. But in the books, Spencer had a memory of pushing "Alison" (actually Ali's twist sister Courtney, but that's another issue) to the ground, leading her to think for some time that she was the one who killed Alison. Maybe something like that is happening here?

What do you think of this theory — is it possible, or totally crazy? Sound off in the comments below.

Find Pretty Little Liars spoilers here.

Catch the Pretty Little Liars Season 4 winter premiere on Tuesday, January 7, 2013 at 8 p.m. ET on ABC Family.

Rebecca Martin is an Associate Editor at Wetpaint Entertainment and our resident Game of Thrones, Breaking Bad, and genre TV expert. Follow her on Twitter and Google+!