Episode 2 starts off with the budding romance between Karen and Tyreese. After saying goodnight to each other Karen heads off to cell block D, but stops off in the bathroom to wash up before bed. Unbeknownst to her, Patrick (Carl’s friend) is laying dead in the bathroom. Earlier that day Patrick was complaining of feeling sick, later that night he stumbled into the bathroom and fell dead on the floor. Patrick follows Karen to D block and soon the mayhem begins. He starts feeding on the inhabitants of the cell block and shortly more zombies rise. At dawn Rick and Carl, already outside working in the garden, hear gunshots. Rick tells Carl to stay with Maggie in the guard tower, while he rushes in to find out what s going on.
After cleaning out the zombies from cell block D, Rick, Glen and Daryl discover that Patrick was the cause of the outbreak and that there is a dangerous flu going around.
Hershel calls a gathering of the council to decide what is the best plan of action, and they decide the most important thing to do first is to quarantine everyone in cell block D as well as those who cleaned it out. The number one priority is to contain the problem before it spreads.
Meanwhile the zombies outside the fence have started to gather en masse along the fence, someone has been feeding them rats and the sound of the guns inside the prison has further drawn them toward the prison. The sheer number of zombies pressing against the fence is threatening the integrity of the barrier and they almost cause it to collapse. To draw the zombies away from the fence Daryl and Rick drive out with the pigs and drop them one-by-one into the path of the zombies. This gives them time to reinforce the fence on the inside.
The threat of attack on the outside has been neutralized – for the time being – but for now they must address the greater problem at hand – how to cure the people of the virus.