At the end of the penultimate episode, Mare (Kate Winslet) drives to the cabin where brothers John Ross (Joe Tippett) and his brother Billy (Robbie Tann) are fishing in order to arrest Billy for the murder of his niece Erin McMenamin (Cailee Spaeny). It all seems to be warranted — after all, Billy confessed to John that he killed Erin, and Lori Ross (Julianne Nicholson) told her best friend Mare about the confession even when her husband John asked her to keep it secret. However, at the very end of the episode, Chief Carter (John Douglas Thompson) is handed a photo from Erin's journal that seems to offer another theory. We don't see the picture, but it's enough of a revelation that he needs to alert Mare right away. Could she have the wrong guy?
Yes, another red herring. This one proved to be too much for viewers — and fans on Twitter have been, understandably, spiraling.
Here's the reigning theory: John is actually the father of Erin's child and killed her (or had her killed, possibly by his brother).
Yes, some fans actually attempted to freeze frame the photo and enhance, but there are some other clues that have us thinking this way. For one thing, we know John is a repeat cheater, and this time Lori even said he was so good at lying that she didn't even suspect it. Neither he nor his son specifically said it was with the same woman he slept with before, either. Then there's the fact that he basically coached his brother to confess ("Say, 'I killed her'"), and then told his wife to keep Billy's involvement a secret in order to "protect their family" — but how do we know they weren't talking about himself? John could also be the father and used his gift of manipulation to get Billy to kill Erin. And then there's also the receipt from the jeweller where Erin's necklace was purchased, which just says “Ross” and no first name.
When Billy earlier in the episode angrily tells his brother, “You made a mess of your life because you couldn’t keep your dick in your fucking pants. Now you clean it up!” he seems to be referring to John's affair, but he could be talking about Erin.
Whatever happens in the Mare Of Easttown finale, we know it won't be simple. See you next Sunday for the next rollercoaster ride.