Three years into the zombie apocalypse, a ragtag team of everyday heroes comes together to transport the only known survivor of the zombie virus from Upstate New York to a lab in California, in hopes of using his blood for a vaccine. A zombie baby proves to be an early obstacle, and what they don't know is that their last, best hope for a vaccine is hiding a dark secret that threatens them all.
In New Jersey, the survivors run out of fuel and embark on a dangerous mission to replenish their supply. Meanwhile, Cassandra's past comes back to haunt her.
The survivors make their way through the mean streets of Philadelphia, where they cross paths with a group of psychotic outlaws with ties to one of their own.
The survivors visit Warren's home town in Central Illinois, but will they find her long missing husband? Oh, yeah - there's also a zombie tornado that leaves everyone in danger.
As they travel across Nebraska, the group finds themselves trapped in a morgue as a literal zombie tsunami engulfs them; at the same time, Citizen Z gets a visitor who might not be who he seems to be.
Murphy is kidnapped by a group of outlaws trying to crack the "Fort Knox of Oxycontin." As the survivors battle drug-enhanced zombies, a startling discovery is made about Murphy's abilities.
