Elsewhere in the camp, Carol says her own bitter goodbye to her abusive husband Ed, who was the first bitten in the attack. Though Daryl has apparently been designated official zombie dispatcher, Carol asks to ensure that Ed doesn't get back up personally. As she repeatedly drives the pickaxe into his skull, it's clearly cathartic—revenge after all the abuse he inflicted on her (and likely, as last week's episode implied, on their daughter). But there's an honest level of grief in her actions, too; though she'll certainly be better off without Ed, his death makes her even more alone, and in a world with so few real people left, even an abusive relationship isn't easy to say goodbye to.

However, the episode's most complex quandary comes in the form of Jim, who Jacqui realizes was bitten in the attack. Jim's infection represents a clear threat to the group, and Daryl wants to dispatch him like they would any other zombie, but Rick convinces the group to venture to the CDC in a last-ditch effort to save him.

Jim's declining health provides the first clear insight into exactly what happens to the infected in The Walking Dead. As the effects of the bite take hold, Jim grows ever more feverish, exhausted, and incoherent, and it's clear that it won't be long before he's just another zombie. Rick refused to let Daryl kill Jim because it would be crossing "the line," but an unspoken question lingers: where is the line? When Jim gets glassy-eyed? When he loses the ability to speak? Or—despite the severe risk to the group—after he tries to bite someone for the first time?

It's a question the survivors may have to face someday, but in "Wildfire," Jim spares the group any queasy moral decisions by asking to be left behind. His request protects the group from danger, but it's also a profoundly personal decision. By making a final choice for himself before he loses the ability to choose at all, Jim asserts his fading humanity one last time. In a world where the line between the dead and the living is so blurred, there's no more powerful gesture to make.

Shock of the Week: The audience is suddenly introduced to Jenner (Noah Emmerich), a solitary survivor within the CDC who's conducting unexplained experiments on zombie flesh.

Zombie Survival Tip: If you need to make sure that a bunch of defeated zombies stay dead, there's nothing faster or more effective than a pickaxe to the brain.