We finally got the rest of those details about Bethany Young and the DiLaurentis family. And it wasn't pretty (pun intended). Pretty Little Liars ' #FatalFinale killed Mona but not before she could drop the most important reveal the series has ever given fans. Alison probably killed Bethany Young all because the poor girl knew way too much. After Alison did her best during her lie detector test with the Rosewood police to incriminate Spencer in Bethany's murder, Mona and Spencer did some investigating of their own at Radley. And what they found was surprising, terrifying, and totally out-creeped anything PLL's done in the past.
Ali and Bethany knew each other and, apparently, their parents did as well. According to tapes and files Spencer and Mona found during their spy-mission to Radley, Mrs. DiLaurentis and Bethany Young's father were having an affair just before Bethany was killed. The tapes, from Bethany's therapy sessions at the facility, revealed how she knew Mrs. DiLaurentis, that she knew Alison, and that she was aware of her father's affair with Mrs. D.
Well, that didn't go over well with Ali when she found out. Mona's analysis of the tapes — before she was brutally MURDERED, mind you — revealed that Alison lured Bethany to Rosewood to kill her. Which just makes the idea of Alison being "A" even more terrifying. IF Ali did do this (we don't have any real proof, except for the fact that she knew Bethany and about the affair) it would mean that she took a significantly long time to plan it. She planned to dress Bethany exactly like her, she planned this sleepover to cover it up, and she planned to fake her own death.
This all has "A"s fingerprints all over it. Could this be the final nail in the "Ali is 'A'" coffin? PLL's sure making it seem like it.
Image: Eric McCandless/ABC Family