A-Tag: A puts some kind of Emily-killing poison into Emily's shit, slowly poisoning her and more importantly leaching away her ability to deal with Hanna's ten miles of bullshit all the time.
Next week: Spencer bludgeons Garrett to death with whatever's handy in a cop car, but immediately forgets she did that. Hanna walks in on her parents doing it, Emily walks in on Hanna and Caleb doing it, Pam somehow psychically knows when Emily and Samara are doing it, everybody is doing it. Jason and Ezra get some complex stuff going on between them, but when Aria walks in on them doing it, she assumes they're fighting over her and runs off to sulk and wait for them to chase her, and they never do, and she ends up starving to death waiting for this moment, under the stairs or wherever.
Emily loses her vision for a short time, thanks to being poisoned; she tries to make pottery friends with Jenna but Jenna calls her a wannabe hipster who's just going blind to seem cool. Mike Montgomery blows absolutely everybody to Hell and everybody loses their office pool because 80% of everybody assumed it would be Lucas that ended up gunning everybody down and the rest assumed it would be Mona Vanderwaal. Including, it must be said, Mona Vanderwaal.