"Isolation" is the third episode of the fourth season of AMC's The Walking Dead. It is the thirty-eighth episode of the series overall. It premiered on October 27, 2013. It was written by Robert Kirkman and directed by Daniel Sackheim.
In the inner courtyard, Tyreese explains to Rick, Carol and Daryl how he found Karen and David's charred corpses; he came to see Karen, saw the blood trail on the floor, and it led him outside. There he discovered that both had been murdered in cold blood. Tyreese demands that Rick find who did it and bring the killer to him; when the latter tries to calm him down, he turns violent and attacks him, punching him in the face twice. Daryl holds him back, and Carol tries to stop Rick from retaliating, but it's too late. Rick charges at Tyreese, knocking him down and brutally beating his face. Daryl eventually pulls Rick off of Tyreese before it can go any further. Rick looks at his severely injured hand, horrified at what he just did.
Dr. S and Hershel are looking over a bite victim, who got his arm amputated. Unfortunately, the victim dies of blood-loss. Dr. S reluctantly prepares to put him down. Later, Hershel is seen bandaging Rick's hand. He comments on the group's situation, and that "everything they worked so hard to keep out just found its way in" and briefs Rick on the flu situation; it is spreading, and another council meeting is to be held the next day to make a final decision as to what they should do. Tyreese is seen digging graves for Karen and David. Bob approaches him, telling Tyreese to go see Hershel and make sure he's alright. Tyreese firmly says that he will, but only after they are buried. Bob tries to change Tyreese's mind, but Tyreese glares at him and repeats, "Once they're in the ground." Bob then starts to help him dig.
Glenn suggests to Hershel that, with Karen and David dead, the infection may have been cured after all. Sasha suddenly leaves C-Block, coughing violently. She assures Hershel that she will go to A-Block - where all the sick people are being isolated - to see Dr. S, who is revealed to be sick as well. At the meeting the following morning, the council eventually reach the consensus that they need antibiotics in order to start the treatment. Hershel mentions that there is an animal hospital facility that may have what they need and may have been overlooked by scavengers, however it's 50-miles away. Glenn starts to show symptoms of the flu.
The sick are led into Cell Block A while Carol watches over them, wearing a mask for protection. Suddenly, Lizzie comes over and tells Carol that she is not feeling well. She asks if Carol can tuck her in, but Carol realizes that she might get infected. Heartbroken, Carol gives her a hug and sends her inside the cell-block to Glenn, before tearing off her mask and sobbing.
Outside, Carol is pumping the water, pointing out to Rick that the pump's intake hose, which is outside the fence, is sucking up mud. They agree that the next day they will go outside the perimeter to fix it. She suggests to Rick that he should talk to Tyreese, before heading back to the prison. Rick cautiously approaches Tyreese who is finishing the graves. He says that he's sorry for everything that happened. Tyreese congenially admits that there was wrong-doing on all sides. Rick then proceeds to ask him if Karen and David had any enemies or anyone who had a big problem with them. Tyreese fiercely denies this and then walks off, criticizing Rick for spending the day "looking at water pumps" instead of trying to find the murderer.
In the cell block, Rick briefly talks to Carl to look over the office block, where the most vulnerable survivors, the young kids and the elderly, are being kept. Bob and Daryl fuel up a car, and Bob is disturbed when Daryl reveals that it was Zach's car. Back in A-Block, Tyreese, begins to post himself as guard to ensure that no one will try to kill them. Daryl asks him to join the run for medical supplies with Daryl, Michonne and Bob. He refuses at first, but Daryl is able to convince him otherwise, saying he'll help them more by getting the medicine than there, watching. He bids farewell to a sick Sasha, and leaves with the team.
In the office block, Hershel decides to go into the woods, hoping to find elderberries to treat the patients. After a tense moment with Carl, who insists that he go along with Hershel, they reach an agreement wherein Carl goes out with him. Outside, Hershel comments that he'd be good without him, and remarks how peaceful it is out there. How safe is out there compared to the Prison. Carl disagrees, pointing out to a nearby, severely-decomposed walker, and soon one more shows up with an animal trap clamped to its leg. Carl prepares to shoot it, but Hershel stops him and tells him that he doesn't need to. Carl realizes that Hershel was correct and they leave the place with the elderberries, with Carl remarking how peaceful it was.
Rick goes to the Tombs and investigates the courtyard. He examines the blood trail and takes a closer look at the door. There is a bloody handprint on the door and Rick compares the print with his own hand. He notices that it is relatively small, compared to his own. This implies that the killer may have been female. Rick sighs and glances away.
Arriving back at the prison, Maggie sees Hershel entering A-Block and warns him of the sick. Rick overhears the arguing and sides with Maggie. Hershel then proceeds to remind them of how they risk their life everyday and every hour, no matter what they do. He says that it isn't their choice; the only choice being what they are risking it for. Stating that he can help the sick, Hershel pulls a bandanna over his nose and mouth and enters the cell block.
While driving towards the hospital for the supply run, the group hears a faint voice over the car radio repeating the word "Sanctuary...Sanctuary...survive..." Daryl is distracted by it, causing him to swerve several times and hit a few walkers on the road. He stops the car, shocked at the massive herd of thousands of walkers between them and their destination. Daryl drives in reverse and runs over several more walkers, which pile up under the car, lifting the rear wheels and completely immobilizing it. The rear tires spin, splattering blood and gore onto the side panels, forcing them to abandon the car. Daryl, Michonne and Bob make it out and hold their own, but Tyreese stays behind, seemingly in a stupor. Bob's yelling eventually snaps him out of it, and Tyreese storms out of the car. In a rage, he ferociously begins to kill the walkers that are quickly surrounding him, yelling for the others to go, as he is surrounded. After running in the woods for a while, the group stops to rest. They notice movement in the bushes. Tyreese emerges, covered in walker guts and blood, but alive and unscathed. They keep moving, as the walkers chase after them.
Hershel gives Dr. S the elderberry tea. Suffering heavily from the symptoms, Dr. S coughs blood which sprays onto Hershel's face, including his unprotected eyes. Aware that he's most likely infected already, Hershel takes off the bandanna and wipes his face. He also treats Glenn, giving him encouragement to keep pushing through.
Outside, Carol sets up a noise-making distraction machine for the walkers while she sneaks outside the fence to fix the clogged water intake hose. Several walkers emerge from the forest behind Carol, while at the same time, a few of the walkers at the fence turn their attention towards her, leaving her no clear escape. Rick notices this and runs towards her. Carol hurriedly attempts to finish, but drops the fitting into the pond. Rick comes to her aid just in time. They both run back towards the fences and make it back inside. Rick tells her that they agreed to fix the hose tomorrow. "We don't know if we'll get a tomorrow", Carol replies. Rick later confronts Carol in the courtyard, calling her actions from earlier 'moronic'. Carol halfheartedly agrees. As she begins walking away, Rick asks Carol if there's anything that she wouldn't do for the group. After she responds "no", he asks her if she killed Karen and David: After a moment, she replies calmly with a simple "yes."
- At least 2 unnamed prison survivors
- Last appearance of Mr. Jacobson. (Alive)
- The title of the episode, "Isolation", refers to the isolation of the survivors infected with the flu from the presumed uninfected young and old.
- The herd featured in this episode is the largest within the entire The Walking Dead media, including over 7,500 walkers.
- In a behind-the-scenes video on the AMC website, the VFX Supervisor mentions that they turned 100 real Zombie Extras into about 10,000.
- Carl is using the backpack that he, Rick and Michonne took from the hitchhiker in "Clear".
- This episode marks the first time we have seen Carol leave the prison since the group's arrival in "Seed".
- The radio transmission is the first reference to Terminus. The next reference to it will be several episodes later, in "Inmates".
- Rick and Tyreese's fight is adapted from Issue 23.
- Rick looking at his injured hand at the end of the fight is adapted from a similar scene in Issue 17, where he looks at it after beating Thomas instead.
- Hershel stitching and cleaning Rick's hand is adapted from a similar scene in Issue 18, where Dale stitches and cleans it instead.
- Rick investigating the murders is adapted from Issue 18.
- Carol advising Rick to talk with Tyreese to fix their friendship is adapted from a similar scene in Issue 26, where Michonne advises Rick instead.
- Tyreese fighting a herd on the side of the road and being left for dead is adapted from a similar scene in Issue 15, where he fights a group of walkers in the prison's gym instead.
- While Glenn and Maggie are digging graves in the prison yard for the residents killed in the attack on Cell Block D, a prison resident can be seen digging alongside them, despite dying in the attack in the previous episode.
- Because scenes are sometimes filmed out of episodic order, his presence was most likely an oversight by the crew of the show.