Episode 1 "What Lies Ahead"
The group heads toward Fort Benning but is blocked by a pileup of vehicles on the interstate and further delayed when the RV blows a radiator hose. A depressed Andrea expresses resentment towards Dale for not being allowed to die in a way of her choosing, since he forced her to save him from the CDC explosion; contrarily, he feels he saved her. Shane tells Lori he has decided to leave the group when he has the chance. The group narrowly avoids most of a herd of walkers passing the pileup, but two of them chase Sophia into the woods. Rick distracts and kills her pursuing walkers, but she goes missing in the process. During a search for Sophia, the group stops at a rural church, at which point Andrea privately asks Shane if she can join him when he leaves the group. As the search continues, Rick, Shane, and Carl come upon a buck; as Carl approaches the animal a gunshot passes through the deer into him.
Episode 2 "Bloodletting"
In a flashback to a time before the apocalypse, Shane tells Lori that Rick has been wounded in a highway shootout, and Lori in turn tells Carl. In the present, Carl has been accidentally shot by a hunter named Otis. Otis directs Rick, Shane, and Carl to the home of veterinarian Hershel Greene, who manages to remove one of six bullet fragments. One of Hershel's daughters, Maggie, is sent to Sophia's search party and returns with Lori to the Greene home. Rick gives blood to Carl, while Otis and Shane go to the former FEMA aid station at a walker-infested high school to gather urgently needed medical supplies. Dale and T-Dog wait at the RV; Dale fears that T-Dog may have contracted an infection from his injury, and the two search for antibiotics. Shane and Otis find the necessary supplies at the FEMA aid station; however they are forced to barricade themselves in the school's entrance after walkers surround them.
Episode 3 "Save the Last One"
Hershel tells Lori and Rick that he might need to perform Carl's surgery without a respirator if Shane and Otis do not return soon with the necessary medical supplies. Daryl and Andrea return to the forest to search for Sophia, and Daryl shares a childhood memory of being lost in the woods. The two then come upon a zombie hanging from a tree, where he had attempted to kill himself before transforming and ended up having his legs eaten; Daryl kills the zombie, but only after Andrea agrees to answer his question concerning whether she wants to continue living or kill herself. Glenn and T-Dog arrive at the Greene home, where T-Dog's injury is treated while Glenn and Maggie talk about faith. Lori contemplates letting Carl die to end his suffering from living in the world as it now is, while Rick holds to the belief that Carl may yet live in a better future. Meanwhile, Shane and Otis fight to escape the high school, only to face more walkers at every turn. Just as they are about to run out of ammo, an injured Shane incapacitates Otis, so he can escape the walkers. Shane then takes the supplies from Otis and watches as the horde of walkers rips Otis apart. Shane returns alone to the Greene home with the critical medical supplies, just in time for Carl's surgery. Shane misleads everyone about Otis' death and shaves his head, both as a sign that he has completely changed his way of thinking in this new world and in order to eliminate the one thing (his hair) Otis was able to grasp when the crucial moment came.
Episode 4 "Cherokee Rose"
Dale, Daryl, Andrea, and Carol arrive at the Greene home and set up camp as Carl recovers. Since Shane is still injured and Rick is weak from blood loss, Daryl decides to search alone for Sophia. He does not find her but instead finds a Cherokee rose (a Native American symbol for the tears of mothers on the Trail of Tears) and gives it to Carol. Hershel takes Rick on a tour and tells him that he and his group should leave the property after Sophia is found and Carl heals. Rick begs Hershel to reconsider, and Hershel says he will consider letting them stay if they follow his rules. While Dale and T-Dog are retrieving water from a nearby well, they realize that there is a walker inside. Since the survivors cannot kill it, as doing so might infect the water, they decide Glenn will act as bait to snare the walker, so that it can be removed from the well. They succeed in roping and raising the walker, but just as it is being pulled out of the well, its legs and internal organs break off and spill back into the well, thoroughly infecting the water. T-Dog then kills the walker. Maggie and Glenn head to a local pharmacy for supplies, where Maggie offers to have sex with Glenn and he accepts. Glenn retrieves a pregnancy test, requested by Lori; Lori later uses it and realizes she is pregnant.
Episode 5 "Chupacabra"
The survivors continue to search for Sophia, but Hershel is growing increasingly concerned about their presence on his land for unclear reasons. Shane and Rick argue over whether or not to continue the search, with Shane arguing that it's time to cut their losses and leave. Rick is angry with him but later begins to wonder whether Shane is right. While out searching for Sophia, Daryl finds her doll but subsequently falls off a ridge and is badly injured. He has hallucinations of his brother Merle but snaps out of it in time to deal with two attacking walkers. He then finds the strength to climb up the ridge and return to the farm. He eats squirrel, raw, and as he approaches the farm, face bloodied and limping, Andrea mistakes him for a walker and shoots him in the neck, wounding him. Maggie passes a note to Glenn asking to meet for a sexual encounter. Glenn passes it back, saying to meet in the barn. A horrified Maggie attempts to stop him, but she is unable to prevent him from discovering the barn is full of captured walkers.
Episode 6 "Secrets"
The group practices their shooting skills and Andrea performs well. Glenn tells Dale about the walkers being kept in the barn. Dale confronts Hershel about the barn and Hershel explains that the walkers in the barn are family members and neighbors and are "still people"; that they are merely sick and are being contained so they can be cured in the future. Lori sends Glenn and Maggie to the pharmacy to get morning-after pills. Maggie gets attacked by a walker and Glenn kills it. In a fury, Maggie gives Lori the pills and yells at her for almost getting them killed. Glenn gives Lori prenatal vitamins as well. Lori takes the morning-after pills, but forces herself to vomit them up. Shane and Andrea go looking for Sophia in a nearby town and are surrounded by walkers. Andrea and Shane kill enough of them to flee safely. Andrea, feeling empowered, comes on to Shane on the way back and they engage in sexual relations. When they arrive at camp, Dale recognizes something is going on between them. Out of concern for Andrea, he confronts Shane about what really happened the night Otis died, as Dale seems to have figured out that Shane killed him in order to save himself. Shane threatens Dale. Rick finds the empty morning-after pill package and confronts Lori. They debate the ethical decision of bringing the unborn child into a world infested with walkers. Lori confesses to having had a sexual relationship with Shane when she thought Rick was dead.
Episode 7 "Pretty Much Dead Already"When Glenn reveals to the group that walkers are being kept in the barn, Rick discusses the matter with Hershel; Rick also tries to convince him to let the group stay, especially since his wife is pregnant. Rick tells Shane that Lori is pregnant and Shane confronts her, knowing that her child may be his. Dale tries to hide the group's guns in the swamp but fails when Shane catches him. Against Hershel's and Rick's wishes, Shane hands the guns out to members of the group. Hershel tricks Rick into helping him recover some walkers stuck in quicksand, and tells him that his group can stay so long as they do not kill the walkers. As they return, Shane sees the captured walkers and becomes enraged. He repeatedly shoots Hershel's captured walker in the chest, asking why it doesn't die if it is a living, sick person. He then shoots it in the head as Hershel looks on. Shane breaks open the barn door, forcing the group to shoot all of the captured walkers. Thinking all the walkers are dead, the stunned group watches as the missing Sophia comes out of the barn as a walker. Rick remorsefully steps forward and shoots her in the head.
Episode 8 "Nebraska"
After the destruction of his walker-family, Hershel demands that Rick and his group leave immediately. Shane accuses Rick of being just as delusional as Hershel, saying that Hershel knew about Sophia the whole time and hid her from the group. Dale tells Andrea to be careful about her relationship with Shane, since Dale knows what kind of person Shane is and now wants him gone from the group. He also reveals this to Lori, including his assumption about Otis' fate. Hershel goes missing, but Rick and Glenn find him in the town bar, drinking and lamenting the folly of his hope of a cure for his family. After Rick convinces him to return to his family, two men named Dave and Tony enter the bar and request refuge at Hershel's farm. Rick, Glenn, and Hershel learn from the two men that Fort Benning is overrun. When Rick flatly refuses them safe haven, Dave draws his firearm, but Rick is quicker on the draw and kills him and Tony. Hershel's daughter Beth is rendered unconscious from an unknown ailment, leading Lori to drive into town to retrieve Hershel. Lori hits a walker on the road and flips the car. The episode ends with Lori's fate unknown and Shane and T-Dog setting fire to the dead walkers from the barn.
Episode 9 "Triggerfinger"
After killing their attackers, Rick, Hershel, and Glenn prepare to leave, but three other men, looking for Dave and Tony, enter the town before they can escape. Lori escapes from two walkers and continues down the road on foot to look for her husband. Rick, Hershel, and Glenn inadvertently get into a gunfight with the others. Back at the farm, Carol tries to talk to Daryl and is rebuffed the same way Lori was. When they realize Lori is missing, Shane goes down to help her and convinces her to come back by telling her that Rick and the others are already back. When she finds out he lied, he reveals that she is pregnant. Carl asks to name the baby Sophia if it is a girl. Shane and Lori talk about their past relationship; Shane is convinced it was real. In town, Hershel shoots one attacker, who is then killed by walkers. Another attacker attempts to jump from a building into their truck, but instead impales his leg on a gate, causing the third man to abandon him. Rick, Hershel, and Glenn rescue the injured attacker and bring him to the farm. Rick plans to send him away once he is healed, but Shane disagrees. Lori tells Rick that Shane is dangerous.
Episode 10 "18 Miles Out"
Rick and Shane have a roadside discussion about Shane's feelings for Lori and about the circumstances surrounding Otis' death, with Shane questioning his friend's ability to make the hard decisions. They are taking the wounded man from the previous episode 18 miles out from the farm to abandon him. The man begs them to let him stay, inadvertently revealing that he knows the location of the farm. Shane wants to kill the man, but Rick says that he needs to think about it first; their disagreement leads to a fight, which attracts a group of walkers. All three barely make it out alive. Back at the farm, Beth has given up on life and is contemplating suicide. Both Lori and Maggie attempt to talk her out of it and want to place her under watch, but Andrea says Beth needs to find her own reasons to keep living. Beth locks herself in the bathroom and uses a piece of broken mirror to slit her wrist, but Lori manages to break open the door before she bleeds out. Maggie and Lori are furious with Andrea for not keeping an eye on Beth; Andrea defends herself by saying that Beth no longer wants to commit suicide and Hershel was able to save her. Rick tells Shane that he needs to follow his (Rick's) lead from now on. They then put the injured attacker back into the trunk and drive back to the farm.
Episode 11 "Judge, Jury, Executioner"
The group has Randall in custody, and Daryl tortures the prisoner for information. Randall reveals that his old survivor group is heavily armed and contains thirty male members; some of those members once raped a pair of teenaged female survivors and forced their father to watch. This convinces the group that letting Randall live is a huge risk. Dale, horrified that the group is actually considering executing Randall, tries to convince everybody that they must not sacrifice their humanity. Meanwhile, Carl wanders into the forest and finds a walker trapped in mud. Carl tries and fails to kill it and flees when it starts breaking free from the mud. Back at the farm, Dale fails to convince the group to stop the execution. Rick, Shane, and Daryl take Randall to the barn to execute him, but Rick hesitates when he sees that Carl is watching. He then decides to delay the execution. Meanwhile, Dale encounters a gutted cow dying in the field. When he turns around, he is attacked by a walker and has his stomach ripped open. Daryl kills the walker, and Carl is shocked to see that it was the same one he had failed to kill in the forest. Daryl then mercifully kills Dale in order to end his suffering.
Episode 12 "Better Angels"
The group holds a brief funeral for Dale. Rick asks the group to stay united, despite Dale's warning that the group is "broken". They work together to prepare for the coming winter, by stockpiling supplies and clearing walkers from the surrounding area. However, there is still the issue of what to do with Randall. Rick ultimately decides to honor Dale's memory by sparing Randall's life and plans to drop him off somewhere far away from the farm. However, Shane frees Randall from the barn and leads him into the forest, where he breaks Randall's neck. Shane then returns to the farm and tells the rest of the group that Randall escaped. Rick, Shane, Glenn, and Daryl go into the forest to track him down. Glenn and Daryl split off from Rick and Shane and encounter Randall, who has somehow turned into a walker, despite the lack of evidence of his having been bitten or scratched. Glenn then kills Randall again, by impaling him through the head with a machete. Meanwhile, Rick tells Shane to admit he plans to murder him. Shane holds Rick at gunpoint and they argue about who would be a better father to Carl and husband to Lori. Rick talks Shane into putting his gun down. Knowing he has to kill Shane, he stabs him in the heart. Carl arrives and appears to have pulled his gun on Rick, but then aims behind his father and puts a bullet into the head of a reanimated Shane (who, like Randall, also had no evidence of being bitten, and who - after Rick stabbed him - seemed to experience intense and disturbing zombie-like thoughts). Meanwhile, a massive number of walkers, drawn by the gunshots, are shown headed towards them.
Episode 13 "Beside the Dying Fire"
Shortly after Shane's death, a massive horde of walkers attacks the farm. The survivors attempt to fight off the horde but are quickly overwhelmed. Jimmy and Patricia are killed, and Andrea is inadvertently left behind. The remaining survivors are forced to scatter in the darkness, but they eventually reunite on the highway where they left supplies for Sophia. Meanwhile, Andrea is still alive and fleeing from the walkers on foot. She is about to be caught by the walkers when she is rescued by a hooded figure wielding a katana and flanked by two leashed, jawless, armless walkers. The other survivors believe Andrea is a lost cause and decide to search for a new shelter, but their cars begin to run low on gas, and they are forced to stop for the night. Confronted with the knowledge that Randall turned into a walker without being bitten, Rick finally reveals to the group what Jenner had told him at the CDC: everybody is already infected with the virus (and will eventually turn into walkers when they die). He also admits that he killed Shane. With this knowledge, the group's morale begins to plummet, but Rick announces that from now on he's in charge, the group will no longer be run as a democracy, and they will find a safe haven from the walkers. As the camera pulls back, a prison complex is visible nearby.