Rick and the gang have apparently been spending the whole winter wandering around the area, trying to avoid zombie herds and getting nowhere fast, other than really skanky-looking. Rick and Lori are barely talking to each other and her baby is clearly due soon, while Carl appears to have undergone some kind of metamorphosis of his own by becoming somewhat competent and mature, even though he's still wearing that stupid hat. The group's about at the end of their rope when they run across a prison. Too bad the yard's full of walkers, though, right? Well, it's bad, but not too bad, as Rick leads the group in a successful operation to clear the yard and seal it off from further incursion. Everyone figures this grassy area inside the chain link fence is their new safe haven, but Rick isn't satisfied; he wants them to force their way into the prison itself, so they can get at the food, medicine, and weapons the place no doubt contains.

So he, Daryl, T-Dogg, Glen, and Maggie fight their way through the inner yard and into one of the cell blocks, which appears safe. There they marshal their resources, explore Rick and Lori's ongoing marital dysfunction, and speculate on what happens if Lori miscarries or dies in childbirth, given the latent zombie plague in all of them. Also, Carl seems to have a bit of a crush on Hershel's youngest daughter Beth, because it's not like he has a lot of other options.

Rick still wants to press on, and he leads all the men and Maggie deeper into the maze of corridors within the prison. Here's where things go wrong, as the claustrophobic hallways remain heavily infested. Soon their retreat is cut off, they're briefly separated from each other, and Hershel is bitten. The group manages to barricade themselves inside a large room, but it's safe to say the mission has gone pear-shaped.

In a desperate move to keep Hershel alive, Rick hacks off the man's leg below the knee. It remains to be seen whether that's going to work, but I don't know if Scott Wilson would have grown his beard and hair out like that if he was going to have to rock that look for more than a couple of episodes. But there might be another cast infusion soon, as the operation is witnessed from behind a grate by five or six humans who have survived inside the prison.

Meanwhile, Andrea isn't alone. The sword-wielding, zombie-keeping figure who rescued her at the end of last season's finale is still with her, which is lucky for Andrea, given this woman's skill with a katana. The bad news is that Andrea is deathly sick, but with walkers accumulating around their small-town hideout, they have little choice but to clear out.

So yeah, remember how irritated we used to get with this show when it was all talking and no zombies? For tonight, at least, that appears to be fixed.