The Walking Dead is a phenomenally popular series. Each episode is immediately followed by a talk show devoted to analysis of that episode. Shockingly elaborate theories have been lovingly formulated about everything from the true father of Lori Grimes' baby to how it is still possible for somebody else to be the killer. Social media explodes into a frenzy with each airing, and riots are regularly threatened if one character or another were to be killed off. Now, with the end of the fourth season approaching, those riots are beginning to feel more and more imminent. This is the time of year when even the characters that usually seem the safest suddenly appear downright killable. After all, popularity does not save characters when it comes to finales on The Walking Dead. "Us" the penultimate episode of Season 4 aired on Sunday, and fans everywhere were relieved to see that all of the main cast would live to fight zombies for another week. In fact, much of "Us" seemed designed more to set up the upcoming episode than to stand on its own. Nevertheless, it was an entertaining hour of television, and it gave viewers plenty to wonder and worry about as we wait for the conclusion. So, without further ado, here is a list of what this episode did particularly well...as well as what didn't really work.