Rick’s group is imprisoned in a train car at Terminus as Gareth and the Terminans prepare to slaughter and eat them. Rick, Daryl, Glenn and Bob are taken to a warehouse and watch as Gareth’s men slit two other men’s throats. Gareth pauses the slaughter to interrogate Rick about a bag he buried in the woods outside Terminus. Rick admits it was weapons, including a machete that “I’m gonna use to kill you.” Before the Terminans can continue, an explosion rocks the warehouse: Carol, outside the walls, has created a diversion, which allows the group to fight their way out of the compound and reunite with Tyreese and Judith.
On the road after fleeing Terminus, the group rescues Father Gabriel, a priest, who is under attack by walkers in the woods. Gabriel leads them to his church, where they take refuge. After Rick grills Gabriel about his past, Gabriel confesses that he locked his congregation out of his church after the fall and allowed them to be devoured by walkers.
During a supply run to a local food bank, Bob gets bitten by a walker, but hides his injury from the group. That night, Gareth and a small crew of surviving Terminans kidnap Bob and eat his leg, returning Bob to the church afterwards to taunt Rick and the others. Gareth’s group storms the church, but Rick’s group ambushes and massacres them. Rick kills Gareth with the machete as promised while Father Gabriel looks on in horror. Afterwards, Bob dies with Sasha at his side.
Glenn, Maggie, Tara, Eugene, Rosita and Abraham leave in a bus to escort Eugene to Washington, D.C. After the bus skids out of control and erupts in flames, Eugene privately admits to Tara that he sabotaged it because he’s afraid he’ll fail the group in D.C. Eventually, Eugene confesses that he’s not a scientist at all and has no idea how to stop the pandemic. Abraham furiously punches Eugene and knocks him unconscious.
In a flashback, Abraham is about to kill himself after finding his family devoured by walkers. When he sees Eugene fleeing from walkers, he stops to save Eugene, who then begs Abraham to help him with a “very important mission.”
Beth wakes up in a bed at Grady Memorial Hospital in Atlanta. Dawn, a police officer who runs the hospital, explains that her officers rescued Beth and that Beth is now indebted to them. She puts Beth to work as a hospital ward to Dr. Edwards.
When a patient dies under Beth’s watch, Beth discovers that Dr. Edwards intentionally instructed her to give him the wrong medication, in order to remain the hospital’s only doctor.
Meanwhile, Officer Gorman, one of Dawn’s officers, makes repeated advances on Beth. Dawn tells Beth to let him have his way. “The happier my officers are, the harder they work to keep us going,” Dawn says. Disgusted by the rampant corruption, Beth decides to escape the hospital with Noah, another hospital ward. While stealing a key from Dawn’s office, Gorman assaults Beth. She throws him to the floor, where he’s torn apart by a patient (Joan) who had recently committed suicide and turned. Beth uses the opportunity to flee the hospital, but is quickly caught. Noah, however, escapes.
Near Gabriel’s church, Daryl and Carol spot a car similar to the one that kidnapped Beth. They follow Beth’s kidnappers into Atlanta and trace the car to Grady Memorial Hospital. They run into Noah while casing the hospital. A hospital car hits Carol and the drivers take her away. Daryl and Noah return to the church, where Rick assembles a team to rescue Beth and Carol.
After the rescue team leaves, Gabriel sneaks out of the fortified church to look at the remains of the Terminan’s camp — witnessing Bob’s charred leg with his own eyes. He inadvertently leads a horde of walkers back to the church. Michonne and Carl trap the walkers inside and escape with Father Gabriel, but are about to be overrun again when Abraham’s group comes back and rescues them.
In Atlanta, Rick’s group kidnaps three of Dawn’s cops — Shepherd, Lamson and Licari — with the intention of arranging a prisoner exchange. When Lamson escapes, Rick chases him down and shoots him dead. Rick’s group meets with Dawn’s group at the hospital to peacefully carry out the exchange. However, Dawn violates the terms by demanding that Noah return to the hospital. Beth, angry and protective of Noah, stabs Dawn with a pair of scissors. Dawn accidentally shoots Beth dead and Daryl in turn shoots Dawn. The remaining officers call a truce and Rick’s devastated group leaves the hospital. Maggie arrives just in time to see Daryl carrying Beth’s body outside.
Some time later, Morgan arrives at Gabriel’s now-abandoned church and finds a map to D.C. along with a note Abraham had written to Rick, “Come to Washington. The new world’s gonna need Rick Grimes.”
After leaving Atlanta, Rick’s group caravans to Noah’s hometown of Richmond, Virginia, only to find that his walled community has been destroyed. Tyreese follows Noah to his old house and gets bitten by Noah’s brother-turned-walker. He starts hallucinating, seeing visions of several people who died: Beth, the Governor, Lizzie, Mika, Martin (a Terminan he fought but didn’t kill), and Bob. Michonne hacks off Tyreese’s arm to prevent the spread of infection, but Tyreese ultimately succumbs to his injuries and dies.
Rick’s group is on the road to D.C. when they run out of supplies. Starving and dehydrated, they feed on feral dogs and look suspiciously on bottled water left for them in the road alongside a note: “From a friend.” After taking shelter in a barn, a man named Aaron introduces himself to the group and invites them to his community in Alexandria. “I think you all would make valuable additions,” he says. Despite Rick’s reluctance, the group goes to Alexandria, a self-sustaining community with its own solar grid, cisterns and eco-based sewage filtration. Deanna, the leader, tells Rick that she picked their group because “I want you to help us survive.”
Rick’s group turns in their guns to the Alexandria armory and receives housing and jobs. Deanna appoints Rick and Michonne as the town’s constables. Daryl becomes Aaron’s recruiting partner. Glenn is assigned to the supply run team and accuses Deanna’s son Aiden, who leads the runs, of incompetence.
Carl meets several of the neighborhood kids and takes an interest in Enid, a girl who also recently came to the community from the outside. They share an intimate moment while running together in the woods.
From the outset, Rick is suspicious of the Alexandrians and perceives weakness. He, Carol and Daryl secretly meet in the woods to arrange stealing guns from the armory, which Carol accomplishes during a welcome party for Rick’s group. At the party, Rick kisses Jessie, one of the Alexandrians, and Sasha explodes at a party guest for worrying about trivialities.
During a supply run, Tara is badly injured and Aiden is killed in a warehouse explosion. In a frantic attempt to escape the warehouse, Glenn, Noah and Nicholas, one of the Alexandrians, are trapped in a revolving door and surrounded by walkers. Nicholas, ignoring Glenn’s pleas, shoves the door open and runs, saving himself but allowing Noah to be devoured by walkers. After escaping, Glenn beats up Nicholas for getting Noah killed and forbids him from leaving Alexandria’s walls. He later follows Nicholas into the woods, where they engage in a brutal fight. Nicholas tries to kill Glenn, but Glenn turns the tables and spares Nicholas’ life when Nicholas confesses that he’s afraid.
While gathering materials to fortify Alexandria’s walls, Abraham rescues an Alexandrian from walkers as everyone else tries to flee. Abraham takes control of the crew. Deanna shares with Maggie her concerns that Rick’s group is becoming too powerful. Then, Gabriel tells Deanna that Rick will destroy everything she’s built.
Carol discovers that Jessie is being physically abused by Pete, her husband, and tells Rick that he’ll have to kill Pete. Rick is shocked to learn that Deanna knows about the abuse but has been protecting Pete because he’s the town’s only surgeon. Rick confronts Pete and they brawl in the street. As everyone looks on, Rick brandishes his gun and screams that their ignorance of the real world is going to get people killed. Michonne knocks Rick unconscious. Afterward, Deanna plans a town meeting to discuss his possible exile.
Out in the woods, Morgan is ambushed by men with “W” scars on their heads. He fights back and knocks his attackers unconscious. Meanwhile, Daryl and Aaron come upon a food warehouse while tracking a potential recruit. As they scavenge for supplies, they trigger an elaborate trap and become surrounded by walkers. Morgan saves them, explaining when Daryl asks why he risked his life for them, “All life is precious.” Daryl notices that Morgan has the map that Abraham gave to Rick.
Gabriel accidentally leaves the Alexandria gate ajar after returning from a walk in the woods. Rick later spots the open gate and a trail of walker blood leading inside. He single-handedly kills all the walkers that have infiltrated the community.
At the town meeting, Rick’s people defend Rick in his absence. Rick finally arrives with a walker corpse in tow and warns that the living and the dead will always find a way in. He vows to teach everyone how to survive. A drunken Pete interrupts the meeting wielding Michonne’s katana and slices Deanna’s husband’s neck when he tries to intervene. With Deanna’s permission, Rick shoots Pete dead. Daryl and Aaron arrive with Morgan, who stares in disbelief at his former friend-turned-executioner.
Meanwhile, the “W” men who attacked Morgan — the Wolves — arrive at the food warehouse and use loud music and disco lights to lure walkers back into the shipping trucks, resetting their trap. One of them looks through photos of Alexandria and pauses at a snapshot of Rick and Carl. At the now quiet food processing plant, the recruit that Daryl and Aaron were following is now a newly turned walker, stumbling past a graffiti message on a wall that says “WOLVES NOT FAR.”