The 5 most convincing theories about the Big Little Lies season 2 finale.

SPOILER ALERT: This post contains spoilers for Big Little Lies season one and the first four episodes of season two.

Be prepared, Big Little Lies fans.

There are just three episodes of Season 2 of the HBO drama to go.

And it looks like all the lies, big and little, are about to unravel.

With the show having passed beyond Liane Moriarty’s novel of the same name, fans are sharing all their theories concerning what the season finale will entail.

And let’s just say, we think Mary Louise (Meryl Streep) will have everything to do with whatever the ending will bring.

Watch the official trailer for Big Little Lies Season 2 below. Post continues after video.

Here are the five best, most convincing theories about the Season 2 Big Little Lies finale.

Celeste will kill Mary Louise.

One Reddit user thinks Mary Louise's pursuit to unearth what happened to her son Perry will come to a grim end. And with Mary Louise now seeking custody of Celeste's boys, Max and Josh, the tension between the two only continues to grow.

"I bet ML [Mary Louise] will die at the hands of Celeste and/or the group when she discovers too much."

Season One wrapped with Bonnie (Zoë Kravitz) pushing Perry (Alexander Skarsgård) down the stairs to his death, so will Season Two end with another murder?

Bonnie's daughter is Perry's.

Stop.

This would change... everything. And when explained, it actually makes a lot of sense.

This anonymous Reddit user believes Bonnie and Perry had a deeper relationship than we thought.

"I'm convinced that Bonnie had some kind of relationship with Perry," they explain. "She killed him and the show keeps flashing back to her at the Elvis party...

"I think they had an initially consensual affair and Perry started to beat her. She cut it off, but not before he got her pregnant with her daughter. When she saw Perry beating the women at trivia night, she was reminded of her own experience with him and pushed him down the stairs.

"The reason Bonnie [feels] so guilty is because she knows she killed her daughter's father, even though it was justified."

Jane's boyfriend is actually a police officer.

Reddit user ABlokeLikeYou has theorised that Jane's boyfriend is "totally a cop". Please... can Jane not have a break?

"He's got the whole trying a little too hard to be charmingly awkward thing going on, and it's totally a plot device the show would use," he continued.

The fan mentioned his strangely observant behaviour of the Monterey Five as a clue, concluding that the boyfriend is "trying to get close to Jane so she spills the truth."

Marry Louise killed Perry's twin brother.

The mentions of the mysterious death of Perry's twin brother, Raymond, has an ominous feeling to it.

Posted to Reddit, one fan had a convincing conjecture.

"I think Perry got his power/abuse problems from Mary Louise. I think we’ll be shown that in the final episodes that she killed Perry’s brother in a fit of rage or something."

There was a great deal of support for this theory, with another user adding: "The way she yelled at the boys in the car in the first episode leaned me right into the idea that she wasn’t so gentle with her children."

The Detective will prove Perry's violent past.

Reddit user Cupcakeann theorised that there is a "bigger investigation at hand".

"For one senior detective to focus more than a year on someone falling down the stairs, when all witnesses are supporting the same story and Celeste also had the bruising to support the 'he was beating the shit out of her and fell story', seems just weird to me."

Look. They have a point.

"I think she was likely investigating a string of rapes and sexual assaults in the surrounding area over the course of years, [and] she likely had Perry on her radar. When the rapes, assaults completely stopped when Perry died, that probably confirmed for her that it was him, but she needs confirmation of serial violent [behaviour] from Celeste and Jane, just to make she she isn’t wrong about Perry and letting some other rapist off the hook."

So. Many. Good. Theories.

What do you think will happen in the series finale of Big Little Lies Season 2? Let us know in the comments section below!

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For more on this topic:

• The new Big Little Lies theories that explain the mystery of Perry's brother.
• There's a new Big Little Lies theory that spells danger for Celeste.
• The awkward first time Nicole Kidman met Big Little Lies author Liane Moriarty.