'Mare of Easttown' Episode 7 Recap: Who Killed Erin McMenamin Revealed in Series Finale

HBO has now aired the Mare of Easttown finale, which finally revealed to viewers who killed Erin McMenamin (played by Cailee Spaeny)—though not before delivering a few more twists in Mare's (Kate Winslet) investigation. Here's what happened in Episode 7, titled "Sacrament."

Who killed Erin in Mare of Easttown?

In the first half of the season finale, all the clues led to John Ross (Joe Tippett) being the murderer—but things were not entirely as they seemed.

The episode's hour kicked off by revealing what was in the picture brought to police in the prior episode. That photo was of John in bed with Erin.

For viewers struggling to keep up with the many characters of Easttown, John is the husband of Mare's best friend Lori (Julianne Nicholson).

Under interrogation, John revealed to Mare that he and Erin had had a heated confrontation over her son DJ's ear surgery, which led to her brandishing a gun. John said he tried to wrestle it off her, and in doing so, shot her in the hand. He then panicked and shot her in the face, or so he claimed.

The episode then sees John go to prison, and things seem to be reaching a conclusion. We see Mare at the wedding of ex-husband Frank (David Denman), where writer Richard (Guy Pearce) is her date, suggesting she is ready to move on with her life and embrace love.

Not only that, but Mare gets to keep custody of grandson Drew (Izzy King) after his mother checks into rehab.

Sure, Mare keeps watching John's confession as his statement on what kind of gun he shot Erin with does not seem to make full sense, but the show seems to be at its end, with Mare given a happy ending finally.

Just as things seem to be coming to a close, however, the episode is only at its halfway point, and the case of Erin's murder is blown wide open.

The second half of the finale kicks off with Mare making a police visit to Glen (Patrick McDade), the man who revealed at his wife's funeral earlier in Mare of Easttown that he had had an affair with Mare's mom Helen (Jean Smart).

When Glen starts to tell her that things keep going missing from his house, she puts it down to him being a lonely and slightly confused old man not used to doing the kind of chores he now has to take on since his wife died.

However, he mentions offhand that his gun went missing for a while, and Mare humors him by finding out more about it. Going into the shed where he keeps his weapon, she discovers that it is an old police-issued Colt—exactly the same kind of weapon that killed Erin.

Mare has inadvertently found the murder weapon. Asking Glen who had access to this shed, he says only one other person did, the boy who mowed his lawn.

That boy? Ryan Ross (Cameron Mann), the son of John and Lori. After Mare pays him a visit at his school and he runs away, she knows that Ryan killed Erin.

Exactly why he did this is revealed in his interrogation. John had previously had another affair that had nearly split his parents up, and so when Ryan found out his dad was cheating again, he tried to warn Erin off with the gun. The pair got into a scuffle, and Erin was killed.

Mare of Easttown had previously hinted that Ryan was willing to commit violence for what he thought was right—in a previous episode, we saw him attack a boy who had been mocking his sister Moira (Kassie Mundhenk).

The show ends with Ryan going to prison, and Lori and Mare breaking their friendship over what the former saw as the latter's betrayal.

By the end of the show, time has passed, and people are ready to move on. Deacon Mark (James McArdle) is seen giving his first sermon since being released from jail after being falsely accused of murdering Erin. Lori and Mare reconcile, and the series ends with Mare finally ready to go back into the attic where her son killed himself.

Mare of Easttown is streaming now on HBO Max.