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.

An encounter with a seeming Utopian enclave and a religious cult results in a game changer when the survivors travel near Branson, Mo.

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.