Carol and Lizzie keep watch at night while Tyreese and Mika sleep on the railroad tracks. Lizzie asks Carol if she used to have kids. Carol says she had a daughter who "didn't have a mean bone in her body."
"Is that why she isn't here now?" Lizzie asks. Carol nods.
The next morning, Tyreese estimates they're several days away from Terminus. As they follow the tracks, Carol tells Tyreese she's concerned about the girls' survival - believing Mika is too gentle and Lizzie confused about what walkers really are.
Carol and Mika go off in search of water while Tyreese rests his injured arm. A walker advances on Tyreese and Lizzie, but falls into a gap in the tracks, trapping itself. As Tyreese readies his hammer, Lizzie begs him to spare the walker's life. "Sometimes you have to kill them," she admits. "But sometimes you don't."
Meanwhile, Carol implores Mika to toughen up. Mika insists she can kill walkers but won't kill people because it's wrong. Carol says Mika will die if she doesn't change. They discover a house in the middle of a pecan grove. Carol suggests they stay put for a couple of days.
Carol and Tyreese case the house for walkers as the girls wait outside with Judith. Lizzie frets that the adults will find a walker inside and kill it. "They aren't people!" Mika chastises.
A walker attacks Lizzie and Mika, and Mika shoots it dead. Carol and Tyreese race out to check on the girls. As Lizzie cries in mourning for the dead walker, Mika soothes her by instructing her to look at some nearby flowers and count to three.
That night, the group sits around the living room fireplace. Tyreese takes in the peaceful scene and expresses contentment. Mika suggests they make the house their home.
The next day, Carol sees Lizzie playing with a walker in the yard. She runs outside and kills it. "She's my friend and you killed her!" Lizzie screams. Carol says the walker wanted to kill Lizzie, but Lizzie refuses to listen.
While hunting in the forest, Carol tells Mika that she's the smarter of the sisters when it comes to walkers. They spot a deer. Mika aims her gun but ultimately can't pull the trigger. Carol looks on, disappointed.
While collecting well water with Carol, Tyreese suggests that they live at the house instead of going to Terminus. "I trust you," he tells Carol, admitting he's not ready to be with other people yet.
Mika catches Lizzie feeding a mouse to the walker trapped on the railroad track, and admonishes her. "They just want me to change, to make me be like them," Lizzie insists. As she reaches for the walker's snapping mouth, more walkers emerge from the woods. Mika grabs Lizzie and they flee.
Tyreese and Carol hear the girls scream and find them being chased by a pack of walkers. All four form a line and shoot the walkers down.
That night, Carol asks Lizzie if she finally understands what the walkers are. "I know what I have to do now," Lizzie replies. "It's ugly and it's scary and it does change you," Carol says. "But that's how we get to be here."
The next day, Carol and Tyreese hunt together in the forest. Carol warms to Tyreese's idea of living permanently at the house. Tyreese then admits that he's haunted by nightmares of Karen and the person who killed her. Misinterpreting Carol's discomfort as empathy, Tyreese hugs her.
Carol and Tyreese arrive at the house to find Lizzie standing over Mika's dead body, a bloody knife in her hand. Judith lies on a blanket nearby, still alive. "Don't worry, she'll come back!" Lizzie says of her sister. "I didn't hurt her brain."
Carol and Tyreese move to disarm Lizzie, but she aims a gun at them, insisting they have to wait for Mika to wake up. Carol coaxes the gun from Lizzie and dissuades her from harming Judith. Tyreese brings Lizzie and Judith inside. Alone, Carol sobs and then takes out her knife.
That night, Tyreese says he learned that Lizzie had been feeding the prison walkers and wonders if Lizzie killed Karen and David. "It wasn't her," Carol says.
Tyreese suggests he leave with Judith to protect her, but Carol sees only one option for Lizzie: "She can't be around other people," she says.
Carol takes Lizzie for a walk. "Please don't be mad at me," Lizzie wails, sensing Carol's mood. Carol tells Lizzie to look at the flowers then takes out her gun. Moments later, a shot rings out in the forest.
Afterward, Carol and Tyreese dig graves for the girls in front of the house.
That night, Carol gives Tyreese her gun and admits she killed Karen and David. "I had to stop the illness from breaking out," she explains, inviting him to do whatever he needs to do.
Tyreese grips the table, trying to contain his rage. "I forgive you," he finally says. "It's a part of you now. Me too."
The next day, Carol and Tyreese leave the grove with Judith and resume their path down the railroad tracks.