When it first started, The Walking Dead was about the immediate sensation of living in a post-apocalyptic world. In the shadow of a crumbled society, survivors adjusted to the violent realignment of their lives by banding together, struggling to stay human. Now, because of all they've seen and suffered, the characters who've made it this far are shells of their former selves. Survival is no longer simply a matter of avoiding being eaten by zombies; it also requires a frigid sense of detachment and perhaps even cruelty, both of which course through "When the Dead Come Knocking." No one anymore seems to know what it means to be human.
The opening shot of Merle (Michael Rooker) scraping a splintered table with his knife-arm immediately sets the tone for what follows. With Glen (Steven Yeun) shackled and refusing to give up the location of his group, it's not long before Merle begins torturing him. When Merle sets a walker loose in the room, Glen's ensuing struggle to get free and kill exudes a striking primal ferocity. Such a desperate struggle for survival hasn't been seen since Andrea (Laurie Holden) was being chased through the woods at the end of season two. It's a key moment for Glen, too, who until this point in the season hasn't had much of a presence.