Beth, Hershel's youngest daughter, collapses in shock over the barn incident, which included her face-to-face encounter on the ground with her mother-turned-walker who tried to bite her. Hershel disappears to grieve for his wife and other zombified family and friends killed outside the barn. Rick and Glenn find him drinking at a local tavern, then try to coax him to return to the farm. At the tavern, they meet two other survivors (Dave and Tony). The situation rapidly turns sour, so Rick is forced to kill the two men in a gunfight.

The dead men's group quickly finds and opens fire on Rick, Hershel, and Glenn at the bar. The noise attracts a large herd of walkers, forcing all involved to try to flee, but one attacker, Randall Culver, is injured and left behind. Rick opts to take him back to the farm, at the risk that he is likely to reveal the farm's location to his own group. As Rick and the others deliberate about what to do with Randall, a walker bites Dale, forcing Daryl to euthanize him. The group later conducts a search for Randall, whom Shane had secretly released and murdered in the woods. Daryl and Glenn find Randall — as a walker — and kill him. Daryl concludes that Randall died from a broken neck (rather than a walker's bite or scratch) and subsequently reanimated.

Meanwhile, Shane and Rick confront each other — the former having planned the fake search so he could try to murder Rick. Rick gets the upper hand and fatally stabs Shane in the torso. Carl arrives just in time to see Shane reanimate as a walker and shoots him down. The gunshot attracts a large herd of other walkers, who quickly overrun the area. In the ensuing battle and escape, Beth's boyfriend Jimmy and Otis's wife Patricia are devoured, and Andrea is left behind.

Andrea survives on her own and is later rescued by a hooded woman carrying a katana sword and accompanied by two chained, armless, jawless walkers. The remaining survivors regroup but are forced to make camp when their vehicles run low on gasoline. Lori at first shuns Rick after learning that he had killed Shane. After hearing of Randall's fate, Rick finally reveals what Jenner had whispered to him at the CDC: every survivor is infected with the walker pathogen and will thus reanimate after death regardless of its cause.

Rick also discloses to the rest of the group that he was forced to kill Shane in self-defense. Later that night, the group questions Rick's leadership, but Rick asserts a dictatorship-style ultimatum and solidifies his command of the group. In the final scene, a large prison is shown looming in a pan out.