The opening shot centers on the eye of a Walker and expands outward showing the entire head till it gets smashed in by Rick. The survivors have made it through the winter and are scavenging the local area. The past few months have made them a silent and efficient killing unit as they eliminate all the Walker in the house with little trouble. Among the noticeable changes is Herschel growing a beard, Carl getting bigger and firing his own weapon and Lori in the last few weeks of her pregnancy. Without a word they search the home and find little but rests. This time out is short lived as T-Dog sees more Walkers coming. Instead of fighting, the survivors leave and move on.
Finding a place to rest and reassess their supplies, Rick and Daryl head off for some hunting. While on the railroad tracks they see a prison with Walkers inside the gated region surrounding front of the prison. Rick decides it is an opportunity they cannot pass up. The Walkers within are technically trapped and can be picked off without the risk of more getting in if the main gate can be closed.
The survivors make their way into the double fenced area with no major problems. Rick thinks on their strategy while Glen volunteers to make a run for the gate. Rick tells him no and that he would make the run and positions various members of the team in the guard towers to help pick off the Walkers and keep him safe while he makes his run.
Those like Lori, T-Dog and Beth are to try and distract as many Walkers as possible by making noise when Rick runs off. Lori opens the gate and Rick heads out. Rick's movements are smooth and calculated. He doesn't run hard but constant, taking a few Walkers out as needed. One dangerous moment comes when Carol fires a shot just a foot in front of Rick's feet. He eventually makes it to the gate and locks it. Once done, the whole team proceeds to clear the fenced in area of the remaining Walkers. For the first time since they left the farm, they have a huge area that is safe to rest in.
Someplace else, Michonne kills off various Walkers with her sword. She is in an abandoned store and finds some aspirin but little else. Avoiding any other Walkers and without Andrea with her, she leaves
Night falls at the prison and the survivors sit by a fire and relaxes; all except for Rick. He has circled the fenced in area three full times to check for any weak areas. The others note how well of a job he has done and that Shane would not have gotten them this far. Herschel requests his youngest daughter Beth to sing a little for them. She begins alone but soon Maggie joins in and their voices carry softly on the night air.
Rick returns and tells them a plan he wants to do. From his observations, it would seem that the prison fell early in the apocalypse. There could be a large array of supplies inside and it could also be a safe place for Lori to give birth in. The risk could be great but considering the reward and the fact they are running low on ammo, Rick doesn't see any other choices.
Lori follows Rick after he tells everyone what he wants to do. She voices her concern about the plan and it's here where you can see a major rift has carried on from last year when Rick informed the survivors that they all carried the ability to become Walkers. The difference is that now it's Rick that is holding Lori at a distance.
The next morning the survivors prepare to enter one of the prison blocks. Not everyone is going to enter though; only Rick, T-Dog, Glenn, Maggie and Daryl go in to take down the Walkers. They form a close unit and have little problems with the exposed Walkers. But various Walkers that were once prison guards pose a bigger challenge since they are still wearing their riot gear. Daryl's arrows bounce right off the helmets and removing them to get at the head is difficult. Eventually they clear them out and proceed inside the cell block. The Walkers inside are few and some still in their cells which makes them easy to kill off.
The rest of the group enters, brings in their supplies and sets up camp. Beth enters one cell and Carl follows. She mentions that the bed isn't that bad and Carl looks at the top bunk. Herschel comes up behind him and asks if he had found his own cell yet, implying that this one with Beth would not be it. Carl awkwardly leaves that reveals his fondness for Beth.
Michonne enters her temporary hideout and passes her two "pet" Walkers on their chain. She seems surprised for a moment and rushes to the hallway and finds Andrea on the floor. She is very ill and Michonne gives her the aspirin she found earlier. They have both survived the winter together but due to her sickness, Andrea tells her to leave her behind. Michonne won't hear of it. Giving in, Andrea agrees but says they have to leave now or she will probably die there. Quietly and pulling their chained Walkers behind them, they leave the building to search for more supplies.
With the exception of Carl, all the male members of the survivors enter the main hallways of the prison to start clearing it out. Maggie is the only woman to join them and does well except for a moment of getting scared. Glen marks their way back with painted arrows. The corridors are dark and only their flashlights illuminate the area. From behind a corner, numerous Walkers emerge and chase after them. They are too many to fight and other Walkers come from other corridors and descend on the survivors. Glen and Maggie gets separated and hide in a room as does the others.
When things get quiet, Rick's group goes out to find Glen and Maggie. Herschel hears Maggie calling out to them and heads in her direction. A Walker on the floor, whom Herschel thought was just a dead body, rises quickly and bites him in the leg. The pain is excruciating and his screams call both the survivors to him and the Walkers again.
Rushing down the hallway and dragging Herschel, the reunited group finds a large room to get into. It has light coming from some windows and they can see that Herschel's wound is severe. Knowing that doing nothing is a death sentence, Rick wraps a belt around Herschel's leg to cut off the blood and proceeds to hack Herschel's lower leg off. He is doing this in the hope that the Walker induced fever that killed Jim earlier the previous year doesn't happen to Herschel now.
Herschel passes out from the pain but is still losing a lot of blood. Daryl notices movement from the other side of the room. When they shine their lights on the people, they see they are not Walkers but living people who are shocked to see other living people.