'Pretty Much Dead Already' (Season 2, Episode 7)
The second season of may have admittedly stalled a little at first, as Rick and his fellow survivors spent as much time sitting around a farm bickering as they did killing zombies or restarting civilization. But its back half restored some urgency, beginning with this episode in which the group's farmer host Hershel (Scott Wilson) pushes them to leave, and they respond by trying to prove that his Christian compassion for walkers is going to be his undoing. In the brutal final scene, Shane breaks open the barn where Hershel has been holding the zombies he wants to heal, and everyone is shocked to see that among the undead is one of their missing friends, Sophia (Madison Lintz). When Rick executes zombie-Sophia, it's both a reminder of the stakes of the show and a foreshadowing of what's to become of Shane, who — as the episode's title implies — has been slowly losing his grip on humanity.