It's three years after a worldwide zombie virus outbreak. In a period referred to as 'Black Summer' the zombies brought an end to society as we know it. In the last desperate days researchers at the Naval prison laboratory in Portsmouth try to speed up the process of finding a cure by injecting some appointed "volunteers" with experimental vaccines.
Apparently one of these volunteers, Murphy, gets lucky and, even though he's bitten 8 times by zombies, survives. From here Murphy, and more importantly: the vaccine in his blood, needs to get safely to California where there's supposed to be a still functioning lab that can extract the vaccine. This is the last hope for a vaccine that can save humanity.
Z Nation is the ultimate guilty pleasure, full of cheap thrills – a necessary addition to any viewing list.