Nine months have passed. The world has fallen into darkness and the strigoi are in control. The explosion at the end of season three has triggered a global nuclear apocalypse. The resulting nuclear winter liberated the strigoi, allowing them to move about during daytime, allowing the Master to establish a totalitarian regime. The majority of the humans are now working for the strigoi, operating with a single understanding--collaborate or die. In the face of annihilation...do our heroes have what it takes to save humankind?