Armed soldiers drag Madison, Travis and Alicia to a military fuel depot. Troy, the soldier in charge, locks Madison and Alicia in an office and brings Travis to a secret lab where prisoners are killed and tested for resurrection times. Travis finds himself with Nick and Luciana, who are also captive at the lab.
The three escape together. Nick and Luciana are able to hide in the sewers, but the soldiers quickly capture Travis and throw him into an Infected-filled pit.
Troy offers to take Madison and Alicia to safety but, unconvinced, Madison grabs a spoon and plunges it into Troy’s eye socket.
Madison drags Troy outside, holding the spoon in his gouged eye.
Jake, Troy’s brother, arrives and urges Madison to release Troy. He acknowledges that Troy probably brought this on himself, but she’s surrounded and has nowhere to go. Madison releases Troy and
Jake reunites Travis, Madison, Alicia and Nick.
Infected invade the compound. Travis, Alicia and Luciana escape with Jake in a helicopter, while Madison and Nick depart in a truck with Troy.
Troy’s caravan arrives at Broke Jaw Ranch, a survivalist stronghold run by Jeremiah Otto, Troy’s father. Meanwhile, the chopper carrying Jake, Alicia and Luciana is shot from the ground. Travis, fatally wounded, jumps out of the helicopter to his death to help save Alicia. The chopper makes a crash landing.
After Alicia and Jake make their way to the ranch, the Clark family settles in. Alicia befriends a young rancher named Gretchen Trimbol and Nick bonds with Troy while hunting boar.
At the Rosarito Beach Hotel, Strand tries to help Ilene overcome her depression over her daughter’s death. Ilene gives Strand the keys to a car then kills herself. Strand, now banished from the hotel, drives to a water depot to find Dante, a former business associate who now runs a local dam. Dante tries to kill Strand but agrees to spare his life if Strand works for him. Daniel Salazar brings water to Strand in his cell. Strand tells Daniel that Ofelia is waiting for him at a hotel down the coast and begs Daniel to help him escape.
In a flashback, a severely burned Daniel hobbles through the streets of Tijuana. A stranger named Efrain gives him water from a fountain that secretly spouts water at 5 PM every Tuesday. Efrain’s friend, , treats Daniel’s wounds and secures a job for him at the dam. Dante realizes that Daniel was in the El Salvadoran military and enlists him to help track down a water thief. Daniel distracts Dante’s men from the secret fountain, which is run by Lola, by directing them to Efrain’s hideout.
Lola confesses that she was Efrain’s accomplice to save Efrain’s life. Daniel kills Dante before he can execute Lola and Efrain, earning Lola’s trust.
Alicia and Jake start sleeping together.
Troy forms a militia at the ranch. Madison accompanies Troy and several militia members on a search mission to investigate the chopper attack. They discover a ranch founder, Phil, partially scalped outside a ranch outpost. A Native American man named Walker declares that his people attacked the helicopter and outpost to take back the land that rightfully belongs to them. He threatens to kill everyone at the ranch if they don’t abandon it.
Daniel and Strand drive to the Rosarito Beach Hotel only to find it swarming with walkers. Daniel abandons Strand after Strand admits that Ofelia left the hotel while he was still there.
Luciana leaves the ranch to head back toward the border.
Mike Trimbol, one of the militia members, warns everyone at the ranch about Walker’s threat. The Trimbols flee in their RV but are later found dead, the RV riddled with bullets. Troy admits to Madison that he killed the Trimbols after feeling abandoned by Mike, his childhood friend. Madison covers for Troy and leads ranchers to believe that Walker murdered the Trimbols.
Jake and Alicia go to the Black Hat Reservation hoping to parley with Walker. Alicia runs into Ofelia, who was taken in by Walker after nearly dying in the desert. Walker agrees to refrain from further violence in exchange for a tribute and a hostage swap. Alicia stays behind as his hostage, but Madison, Troy and the militia later sneak into Black Hat headquarters and rescue her. Jake admonishes them for undermining the agreement.
Ofelia, bruised and beaten, returns to the ranch and claims that Walker kicked her out because he thought she helped Alicia escape. Ofelia secretly poisons the militia’s coffee, causing soldiers to die, turn and kill more as Infected.
Troy and a team of ranchers steal the Black Hat reliquary to use as leverage against Walker.
Nick confronts Otto with a skull that he found under the floorboards of his adobe. Otto confesses that the remains belonged to Walker’s father, who he killed over a dispute. Madison gives the skull to Walker and offers to return the reliquary in exchange for peace. Walker rejects her terms.
Madison tells Otto that Walker is willing to offer peace in exchange for Otto’s scalp. When Otto refuses to kill himself, Nick shoots him. Madison gives Otto’s head to Walker, satisfying him.
Jake, who believes that Otto offered his life to Walker in to save the ranch, welcomes Nation residents to live beside the ranchers, despite protests from ranchers. Troy, who speaks for a faction of unhappy ranchers, holes up in Otto’s house and begins shooting at Walker’s men. Nick stays with Troy to talk him out of the standoff. The Nation captures them. Walker and Madison agree to exile Troy and temporarily imprison Nick in an outhouse.
A crowd turns on Lola while she distributes water, accusing her of controlling the dam for personal gain.
In Otto’s office, Madison discovers documents detailing low water reserves. She and Walker implement water rationing across the ranch then travel to a trading post to buy more water. In their absence, friction grows between the Nation and ranchers. Alicia unites the communities in a joint effort to build new wells.
Madison runs into Strand at the trading post and learns that he is in debt to Proctor John, the man who runs the trading post. She pays off Strand’s debt using the gold that Walker had intended for the water purchase. She explains to Walker that Strand can lead them to a longer-term water solution: a dam.
Strand brings Madison and Walker to the dam. Lola refuses to make a water deal but offers to let Madison and her family live and work at the dam. Strand secretly rigs a water tanker to explode at the dam, blowing a gate open. An angry mob nearly kills Lola. The incident convinces Lola to give Madison weekly water rations in exchange for guns to protect the dam. They agree to meet in five days to make the first trade.
Troy considers killing himself in exile. He’s stopped when he sees a massive Infected horde, which he corrals and leads toward the ranch. Jake and Nick try to hinder Troy, but Troy fights back. Jake gets bitten by an Infected and dies.
The horde invades the ranch, forcing survivors to flee to the pantry. The pantry’s fan breaks and those hidden there have very little air remaining. While Ofelia and Crazy Dog try to fix the fan, Alicia euthanizes bitten volunteers to help conserve air. She nods off and wakes up to find everyone unconscious or dead. Madison, Strand, Walker, Nick and Troy rescue her as she fights off the Infected.
Alicia ventures off on her own while Madison, Walker and Ofelia drive to the trading post to meet Daniel and Lola. Ofelia reveals that she was bitten and dies moments before Daniel arrives.
Nick and Troy catch up with Madison at the trading post. Nick takes one of Ofelia’s Vicodin, rekindling his addiction. At the trading outpost he finds a man selling a hallucinogenic made from Infected glands and goes on a bender with Troy.
Madison, Strand and Walker accompany Daniel back to the dam, while Nick and Troy stay behind at the outpost.
Alicia meets a woman, Diana, and teams up with her. On their way to the trading post to sell Infected body parts, they get attacked by bandits. Alicia and Diana successfully fight off their assailants, but Diana sustains a severe injury.
Nick and Troy learn that the Proctors are planning to attack the dam. They relay the news to Madison, Strand, Lola and Daniel. The group posts guards at the dam entryways and plants C-4 explosives under the dam to use as a bargaining chip if the Proctors refuse to negotiate.
Walker and Crazy Dog leave Madison’s group to search for members of their tribe.
Eddie, a doctor at the trading post, treats Diana’s injury and commends Alicia’s skills as a medical assistant. He introduces her to Proctor John, who explains that a growth on his spine has hindered his plans to expand his drug empire. Eddie removes the growth with Alicia’s help.
Daniel corners Nick and demands to know how the horde found the ranch. Nick covers for Troy and says that Jake was responsible for the attack. Later, Madison kills Troy after learning that he led the horde to the ranch.
Strand admits to Nick that he made a deal with Proctor John to facilitate a takeover of the dam in exchange for a role as steward of the dam. Nick tells Madison and Troy about Strand’s betrayal. Strand shoots Daniel in the chin when Daniel attacks him for allying with the Proctors.
The Proctors infiltrate the dam, but Daniel’s men fight back. John travels to the dam with Alicia to survey the damage. He kills Lola and discovers Strand trying to smuggle Madison and Nick out of the dam. He decides to kill Nick, Madison and Alicia, but Nick threatens to blow up the dam unless John releases Madison, Alicia and Strand.
As Madison, Alicia and Strand escape in a Zodiac, Walker and Crazy Dog snipe at John’s men from a distance while Daniel attacks the group at point blank. Nick detonates the explosives. The Zodiac gets sucked into a current created by the imploding dam. Madison sinks underwater then swims to shore, where people are filling containers with water released from the dam.