Lt. Hammond gathers a group of ordinary heroes three years after the zombie apocalypse to move the last known survivor of the zombie virus from New York to California in the hopes of collecting his blood for a vaccine.
The survivors run out of gasoline in New Jersey and must embark on a perilous trip to restock their supplies. In the meantime, Cassandra's history returns to haunt her.
The survivors make their way through Philadelphia's filthy streets, where they come upon a gang of crazy outlaws with links to one of their own.
The team is subjected to a very difficult test when they find themselves in a fierce confrontation with former soldiers who have turned into zombies. While they find it very difficult to eliminate them, the life of the only survivor becomes in danger.
The survivors visit Warren's home in town and find her husband, who has been missing, inside. As the couple reunites, an army of zombies invades the area and the team must escape.
When a major confrontation takes place between different religious ideas and the current catastrophe, many things change in the plan that is supposed to be implemented by the team.
While the survivors try to recover from the previous events, a gun confrontation takes place between the team and two mysterious men, attracting the attention of the zombies towards them, and their plan becomes in jeopardy.
As a massive horde of zombies approaches, the group finds themselves trapped in a mortuary. Citizen Z has an unexpected guest who may or may not be who he appears to be.
When the team gets into big trouble, Addy and Mack find themselves lost, and as they try to search for the team, their lives become in great danger.
While contending with luminous and radioactive zombies, the survivors must avert a nuclear meltdown.
The two groups of survivors meet at an all-female commune in Utah, but when one of them is shot, the dream of Utopia is shattered.
Murphy is kidnapped by a group of outlaws, and as the team tries to fend off an army of vicious zombies, Murphy discovers more about his own abilities.
The whole team arrives at a laboratory in Colorado, hoping to find Doctor Merch, who was working to find a cure for the dead and stop the virus from spreading in the world. However, the team discovers that their plan will not go as they expected.