This week on The Walking Dead, we get some exposition up in here, Rick gets bullied into trying to solve a murder, and Hershel continues to prove why he’s my favorite character on the show.

Greetings, gang. Dan is in New York this week getting the goods on some movie news, so I’m filling in for him on The Walking Dead front. Last week a super flu crept into the prison, putting everyone at risk for going walker. The two survivors showing symptoms of the virus, Karen and David, ended up extra crispy for their troubles.

“Isolation” opens with Glenn and Maggie making more graves for the dead lost in the attack by Patrick. Steve Yuen is bringing the puppy dog stare to a whole new level as he tells Maggie with a look that he can’t take much more death. Tyrese, Daryl, Carol, and Rick are surveying the crime scene where Karen and David died. As Tyrese is still reeling from the loss of his new squeeze, he lashes out at Daryl and Rick, with Rick not holding back with a beat down to get Tyrese to put himself together. For someone who’s supposedly survived over a year in the apocalypse, Tyrese sure is a wuss. Rick talks about having been there, but the scariest looking dude in the yard is a giant softie that I don’t believe for a minute could back up the bravado he’s spitting at Rick.

It turns out that the barbecue wasn’t a big success, as everyone else in D Block has contracted the illness. It’s decided that if the group is going to survive this, they’ll need more medicine, and while most of the pharmacies have been picked clean, former vet Hershel thinks the veterinary school will have antibiotics (and plenty of doe-eyed co-ed zombies). This is the one plot point that stands out as somewhat confusing to me: The two docs, Hershel and Dr. S., are in agreement that it’s most likely a super flu, so why are they thinking broad spectrum antibiotics will do anything to help? A flu is a virus and does not respond to antibiotics.

As they begin moving everyone into quarantine, the children and the sole elder of the encampment, Hershel, are sent to the administration building (why are they not using the more comfortable looking building for their daily living?). Carl, who’s slowly become one of the strongest people in camp, isn’t happy about it, but neither he nor Hershel will be in the admin building cooling their heels for long. Hershel knows he can be doing more and isn’t ready to be put out to pasture, a mindset that I know millions of elderly Americans still have. The old farmer isn’t ready for a retirement in the armageddon, so he sets off outside the fences to gather supplies for treating the afflicted’s fevers. Who’s there to back him up? Carl, back in his Sheriff’s hat and ready to roll.

While Daryl and Michonne are gearing up for their trip to the vet school, they start talking about “old days,” and the gaps of what transpired between seasons start to take shape. The away team heading for the college is still a few people light, so Daryl recruits Tyrese, who’s still pissed about Karen and now heading toward the edge with the news that his sister has caught the plague. At first he doesn’t want to go, but after a talk with his sister and knowing the meds are her only hope, he heads over to the transporter… I mean, Dodge Charger to join up. Former Army medic Chris is also taking part, as he is the only able-bodied person capable of discerning what medications will help. Who’s got money down that his alcoholism puts everyone in jeopardy at the college campus? Do vet schools have frat parties?  Chris will perpetually be my bet for “Who’s the red shirt?” on away missions. Before heading out, Tyrese and Carol have a moment where she attempts to console him. The conversation only seems to make matters worse for both of them, as Tyrese heads off even more distraught and Carol is left in a somewhat inexplicable rage.

Upon returning to the prison, Hershel is confronted by Maggie trying to stop him from getting those quarantined the help they need. It’s here that Hershel makes good on the promise that he loves Glenn like a son and lays it out for Maggie. Hershel’s come to grips with the amount of risk there is in the world and, whether he’s in the quarantined area or outside, it’s nothing but danger and risk. “You step outside, you risk your life. You take a sip of water, you risk your life. Every moment now, you risk your life. You don’t have a choice. You can only choose what you’re risking it for. I can help them feel better. I can save lives. That’s reason enough to risk mine and you know that.”

Once inside the cell block, Hershel begins treating the patients with his elderberry cocktail. (Insert Monty Python reference here.) As he treats Dr. S, a character I hope survives, the two come to an understanding that they are men of principle and medicine. They could no more ignore helping another human being as they could putting down a walker. To thank him for his kindness, Dr. S accidentally coughs blood onto Hershel’s face and in his eyes, almost guaranteeing his infection with the super bug.

As the away team heads towards the vet college, Daryl and Michonne begin discussing her search for the Governor, and we learn that Daryl was on the road with her for a good chunk of that time searching as well, but headed back to the prison when the trail went cold. Before they can get into much more detail, they are shocked when a crackling and muddled voice comes across the radio. The road is crowded with zombies and it’s here we get our big zombie fight of the episode. The Dodge Charger is abandoned and as Chris tries to make his way through the crowd of biters he screams for Tyrese to get out of the car. The big man seems to be debating a death wish and finally gets the nerve to evacuate the car, beating his way through the onslaught with his trusty hammer. Oldboy would be proud, until he gets surrounded, and Daryl, Michonne, and Chris write him off as unsaveable. As the team busts ass through the woods, they take a moment to breathe. Two walkers put them on alert, but Tyrese comes through and ends one of the zombies before collapsing to his knees. Michonne makes quick work of the last one and the four of them head off, group intact.

Rick begins a murder investigation to appease Tyrese, and is seen studying the crime scene. The only note he makes to himself is the blood placement on the door where the killer’s hand had to have gone to push it open. Throughout the episode, Rick and Carol have been going back and forth about unclogging the pump that delivers fresh water into the camp. Rick thought he had his final say when he told Carol they’d fix it tomorrow, but, after her conversation with Tyrese, Carol takes it upon herself to go to the creek and clean the hose. Her distraction proves useless and she is about to be beset upon by walkers when Rick makes it to her in the nick of time.

After Rick and Carol make it back to the prison, he confronts her about going for the water when he had decreed they would do it tomorrow. With the best line of the episode, Carol responds, “We don’t know if we get a tomorrow.” At this point, Rick makes a leap and asks Carol if she killed Karen and David, to which she responds with a simple yes. Cut to black. Carol being the killer makes sense and we know she did it for the greater good (“The greater good”), but I’m not sure how Rick made the jump from no leads to eyeing Carol for the crime. If I missed a subtle clue, please point it out to me. As an audience, we could guess it was her from her little freak-out, crying over spilled water, but Rick didn’t witness that, and I didn’t see any indicators of how Rick could come to that conclusion.

Overall, this was a decent epsiode made great by the focus on Scott Wilson’s Hershel. He’s by far the most morally correct character, and the only one that seems to understand morality isn’t just about being justified in your killing. A vet by trade, the doc proved he understood the hippocratic oath in this episode by putting others before himself.  Hershel’s face when Dr. S coughs blood on his eye is by far the most gut-wrenching thing I’ve seen this year, not because of shock or anger, but because his face had nothing but compassion and understanding for his colleague. Even when his death warrant was signed, Hershel would be a man of empathy.

You can get “Isolation” on Amazon and other digital distributors. Tune into AMC next week for an all new episode, stick around for Talking Dead with Chris Hardwick afterwards and then see what we thought by coming here for our recap on Monday morning.