[Editor's note: The following contains spoilers for Mare of Easttown Episode 7, "Sacrament."]

Wow, I really should have paid attention to my own questions. Two episodes ago, when assembling our Mare of Easttown suspect board that’s run in this spot for the last six weeks, I wrapped up the “Whodunnit?” section at the end of the article with this thought:

“What exactly does John and Lori’s son, Ryan, know? We found out this week that he’s keeping a secret with his father that seems to be eating him up from the insides. (Him whaling on that school bully was about more than just seeing his sister get picked on.) If John or Billy is the murderer, does Ryan know about it? Heck, could Ryan actually have fired the killing shot in some kind of confrontation gone horribly wrong? Do we need to add him to the suspect list?!”

As it turns out, the answer to that question was a resounding “YES.” In “Sacrament,” last night’s season finale, everyone’s favorite hoagie-eating detective, Mare Sheehan (Kate Winslet), finally unraveled the full story behind Erin McMenamin’s murder. After hooking up late one night at a family reunion, Erin (Cailee Spaeny) began having an affair with John Ross (Joe Tippett), a cousin to Erin’s father and the husband of Mare’s best friend, Lori (Julianne Nicholson). Furious that his family might fall apart as it nearly did after a previous affair, John’s 13-year-old son, Ryan (Cameron Mann), stole a gun out of Mr. Carroll’s toolshed, arranged a rendezvous with Erin by sending a text from his dad’s phone, and then threatened Erin at gunpoint, demanding that she please stay out of their lives. Erin attempted to grab the gun, a tussle ensued, and Ryan — who, as his mom later says, “doesn’t even know how to hold a gun” – sort of half-accidentally fired the killing shots. Panicked, he called his dad, who, along with her uncle Billy (Robbie Tann), moved Erin’s body in an attempt to cover up the crime.

The plan was for Billy, the family fuck-up, to confess to the crime if Mare bore down on the Rosses. In the finale, John ultimate decides the safer rout is killing Billy and staging it as a suicide, but Mare intervenes and prevents any more bloodshed in a tense showdown by the river. John then admits to the crime and is arrested, but it’s not long before Mare deduces that he’s covering for his son, Ryan, who is the actual killer.

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Image via HBO

Despite my musings about Ryan’s possible culpability two weeks ago, I never did include him as an official entry on the suspect board. I had a hard time seeing how such a young boy could have committed the crime by himself in the middle of the night. I also never added him because, honestly, I couldn’t see any scenario where Ryan as the killer would feel like a satisfactory solution to the mystery. And now that that’s exactly what has happened… well, I’m not sure I was wrong in that regard. Your mileage may vary. I did focus on the Ross family as a whole early and often (Lori has been on the suspect board since the beginning, while the Ross brothers were added in Week 3). All three knew about the crime and attempted to keep the truth from Mare, so I’ll claim partial credit for that. Still, I shouldn’t have underestimated the kid.

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Thanks for reading and playing along as we tried to pinpoint the most likely suspects over this past month and a half. Just to keep the fun going on the way out of the door, I’ll leave you with these questions: Why does the simple act of grass-cutting end up playing such a crucial role in HBO murder mysteries? Here, it was revealed that Ryan knew where to get a gun because he cut Mr. Carroll’s grass, and anyone who watched Season 1 of True Detective knows that lawn maintenance played a part in that show’s final reveal as well. The next time HBO drops a smalltown murder mystery, keep an eye on whoever’s doing yard work.

Secondly, which unresolved question from Mare’s string of subplots is going to pick at you the most? For me, it’s going to be why Mare’s ex-husband Frank lied about having a personal relationship with Erin. There was no reason at all for him to do that — he was just a teacher helping a student! But I guess somebody had to be the chief suspect that week. You may be more bothered by Dylan’s ever-shifting motivations and the fact that the show never did reveal where he went when he left his house late the night of the murder. Just walking around, thinking about burning diaries, I guess.

And then, of course, there’s the final and perhaps most important lingering question: Just what in the heck was Guy Pearce doing on this show anyway?!

Mare of Easttown airs Sundays at 10pm on HBO.

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