After the CDC explosion, the survivors caravan down a highway until the RV breaks down. While scavenging, the group encounters a herd of walkers. In the ensuing chaos, Sophia flees and is lost.
The next day, Rick leads another search, but finds no sign of Sophia. Shane orders everyone to return: He, Rick and Carl will continue.
Later, Carl gets shot while admiring a deer in the woods. The unwitting gunman is Otis, a ranch hand from a nearby farm. Horrified, Otis leads Rick and the gravely-wounded Carl back to the farm. The owner Hershel, a veterinarian, proposes surgery.
Shane and Otis collect surgical supplies from the nearby school.
At the school, Shane and Otis are soon surrounded by walkers. Their ammunition dwindling, Shane shoots Otis in the leg, sacrificing him in order to escape. Shane returns with supplies in time to save Carl’s life and tells the others Otis “told me to keep going.”
Later, Shane checks on Lori and Carl. “Stay,” says Lori.
The next day, Daryl searches for Sophia. Glenn and Hershel’s daughter Maggie plan to go to the pharmacy, where Glenn will pick up a pregnancy test that Lori requested.
Daryl finds a Cherokee Rose blooming outside an abandoned farmhouse — a sign, he tells Carol, that Sophia is still alive.
At the pharmacy, Maggie thinks Glenn’s buying condoms and propositions him. They have sex.
Carl wakes up and declares he’s like Rick now: They’ve both been shot. Rick gives Carl his cowboy hat, then places his sheriff’s uniform and badge in a drawer.
Lori takes the pregnancy test. It’s positive.
Daryl takes Hershel’s horse out on a search for Sophia. The horse gets spooked, tossing Daryl into a ravine. He hallucinates his brother Merle taunting him as he struggles back up the ridge: “Ain’t nobody ever gonna care about you except for me.”
Andrea is sitting watch with a rifle when a bloodied, limping Daryl emerges from afar. Assuming it’s a walker, she shoots and nearly kills him.
Later, Carol brings Daryl food, thanking him for looking for Sophia and assuring him he’s “every bit as good” as Shane and Rick.
Glenn slips a note to Maggie to meet him for sex in the barn, where he discovers walkers corralled inside. “You weren’t supposed to see this,” Maggie says.
Maggie begs Glenn not to tell the others but he confides in Dale. Dale talks to Hershel, who insists walkers are people.
At shooting practice, Andrea shows proficiency. Rick recommends her for Shane’s “advanced class.” But while she’s shooting, Shane flusters her by mentioning Amy.
Shane later apologizes and invites Andrea on a search for Sophia, where they’re soon surrounded by walkers. Andrea shoots an attacking walker in the head, and with newfound confidence takes down the others. Driving back, Andrea and Shane pull over for sex.
At the farm, Lori asks Glenn to make another pharmacy trip for morning-after pills.
In the pharmacy, a walker grabs Maggie. Glenn kills it. Back at the farm, Maggie angrily thrusts the pills at Lori, then tells Glenn he’s being used like an errand boy.
Dale tells Shane to leave, accusing him of killing Otis and trying to kill Rick. Shane threatens Dale in response.
In her tent, Lori swallows the morning-after pills then vomits them up.
Rick finds the pill box, and challenges Lori for going to Glenn instead of him. “I don’t know how we do this,” Lori cries, and then admits to her affair with Shane. “I know,” Rick replies.
The next morning, Glenn reveals that walkers are in the barn. Shane insists they kill them or leave. Rick argues against it since Lori’s pregnant and Sophia’s missing.
Worried about Shane, Dale takes the bag of guns to the swamp. Shane trails Dale and forces him to hand the guns over. Shane brings the guns back and arms the group.
Hershel tells Rick he has to accept walkers as people if he wants to stay. He asks Rick to help corral more into the barn.
Shane spots Rick and Hershel leading two walkers with snare poles. He flies into a rage and breaks open the barn doors. The survivors shoot the dead as they emerge. The final walker to emerge is Sophia. Rick shoots her.
Hershel orders Rick’s people to clear out then heads to an abandoned bar. Rick and Glenn track him down. Two strangers, Dave and Tony, appear. They deduce Rick and company are living at a nearby farm and try to shoot Rick when he refuses to reveal its whereabouts. Rick beats them to the draw, killing both.
Impatient for Rick’s return, Lori drives after him but hits a walker and rolls her car. Shane later finds her on the road. He tells her Rick has returned, thereby convincing her to come back. When Lori discovers Shane’s lie, she becomes incensed.
At the bar, other members of Dave and Tony’s group open fire on Rick, Hershel and Glenn. Walkers approach. The gunmen abandon one of their own, Randall, who’s impaled his leg on a fence. Rick takes Randall back to the farm.
When they arrive, Rick assures everyone Randall’s not a threat, but Shane thinks he’ll lead the others to their door.
Afterwards, Lori warns Rick that Shane “thinks I’m his…He’s dangerous.”
A week later, Rick and Shane drive a blindfolded Randall away to abandon him. Randall reveals he went to school with Maggie; therefore he knows the farm’s location.
Shane tries to kill Randall, but Rick intervenes. Shane says Rick can’t keep Lori and Carl safe. The two brawl until walkers attack.
The three barely escape. Rick blindfolds Randall again and warns Shane, “You wanna be with us, you gotta follow my lead.”
When they return, Daryl interrogates Randall, who says his group has 30 armed men with a history of raping women. Randall swears he’s innocent, but Rick declares him a threat. He must be executed. Dale begs Rick to reconsider.
Rick says Dale can try to convince the others to spare Randall, but in the end, only Andrea sides with him. “This group is broken,” Dale declares.
Carl, meanwhile, finds a walker stuck in a creek-bed. He pelts it with rocks until it gets one leg free.
Rick brings Randall to the barn to execute him. Carl interrupts, urging his father to shoot, which causes Rick to reconsider his decision.
While on a walk, Dale is gored by the walker Carl freed. Daryl mercy-kills Dale.
Dale’s death prompts Rick and Hershel to move the survivors into the house for safety.
Rick orders Shane to establish lookouts while he frees Randall. While constructing a lookout, Shane is approached by Carl, who admits his role in Dale’s death.
Lori, too, approaches Shane, apologizing: “Whatever happened between us,” she says, “I’m so sorry.”
Rick consoles Carl. Dale’s death wasn’t his fault: “People are gonna die,” he says. “Best we can do now is avoid it as long as we can.”
Fed up with Randall, Shane takes him into the forest and snaps his neck. Shane bashes his own face against a tree, then returns and tells the others that Randall jumped him and is on the loose.
Rick, Shane, Daryl and Glenn hunt down Randall. Glenn and Daryl find him: He’s turned into a walker despite not being bitten.
Meanwhile, Shane and Rick come to a clearing, where Rick realizes Shane’s intent to kill him.
Rick tells Shane he ca’’t live with murder and hands over his gun. As Shane looks down, Rick stabs Shane in the heart.
Rick is sobbing near Shane’s dead body when Carl approaches with a gun. Shane resurrects as a walker. Carl shoots him.
The gunshot attracts a nearby herd of walkers who attack the farmhouse. Jimmy and Patricia are killed in the ensuing battle and the group is separated fleeing the farm.
Andrea, alone without ammunition, is about to be killed by a walker when a hooded stranger wielding a katana sword rescues her.
The other survivors regroup on the highway, then caravan away. Hershel’s car soon runs out of gas. Rick declares they’ll camp by the road, sending the group into a panic.
Daryl asks about Randall becoming a walker. Rick reveals Dr. Jenner told him at the CDC that everyone is infected. Rick tells Lori he confirmed Jenner’s secret when he witnessed Shane’s transformation after killing him. Rick admits that he wanted to kill Shane. Horrified, Lori recoils from her husband.
Rick chastises the group for questioning his leadership. He says anyone who wants to leave can. “If you’re staying,” he warns, “this isn’t a democracy any more.”
Up ahead, a structure looms in the distance: a prison.