The latest episode of The Walking Dead, "Killer Within," opens on a hazy morning at the prison where Rick (Andrew Lincoln) and his band of survivors have settled down. The serene atmosphere is offset when a lurking figure opens the gates and baits walkers into the facility. With its dreamlike, foggy setting and a conspicuously waist-down perspective of the saboteur, a peculiar sense of disconnect underlines the implications of what's being depicted. The scene ends with a single close-up of a heart placed on the cold cement. It's a foreboding image that gains magnitude as "Killer Within" gives way to a sudden strike of tragedy. Moreover, the pre-credit sequence lends insight into how the episode amounts to a particularly poignant, if also problematic, entry in the show's run.
I'll return to the significance of the opening scene in a moment. First, let's take a look at how the episode builds to its ultimate disaster through stark tonal contrasts. With apocalyptic shows like this, moments of levity are few and far between. "Killer Within," however, goes so far as to offer something resembling a sustained cheerful mood as it gets going. Now having fortified the prison, Rick guides the crew about the mundane tasks of building a home. Small character moments are peppered along the way and gel nicely together as mini-portraits. Hershel (Scott Wilson) shows progress walking on crutches; Glen (Steven Yeun) and Maggie (Lauren Cohan) get busy in the watchtower; even Rick and Lori (Sarah Wayne Callies) share a brief hopeful exchange from a distance. After a tense encounter with the surviving inmates and a conversation among themselves about whether to allow the prisoners to join their operation, the group is still in better spirits and apparently in control.