While the infected run wild across a broken America, Rick "Ram" Ramacher and Jesse Moreno struggle to make it back home to Northern California. The two slowly come to realize that Ram’s blood may hold the key to a vaccine for the flesh-eating virus and that they have to decide on saving Ram’s family or try to save the survivors of the shattered United States. Invading North Korean and Iranian forces, along with a group of mercenaries, are also searching the ravaged America for Ram and the precious key to an antidote.