When foreman Frank shows new employee Freddy a secret military experiment in a supply warehouse in Louisville, Kentucky, the two klutzes accidentally release a gas that reanimates corpses into flesh-eating zombies. As the epidemic spreads throughout the town, and the creatures satisfy their hunger in gory and outlandish ways, Frank and Freddy fight to survive with the help of their boss and a mysterious mortician.

In this first sequel to The Return of the Living Dead, a group of kids discover one of the drums containing a rotting corpse and release the 2-4-5 Trioxen gas into the air, causing the dead to once again rise from the grave and seek out brains.

Colonel Reynolds and his group of government scientists continue their work on re-animating the dead for military use. His son Curt and his girlfriend Julie use Dad's security pass to sneak in and watch the proceedings. Later when father and son have a disagreement, Curt and Julie take off on a motorcycle and Julie is killed in an accident. Grief-stricken, Curt takes her body to the lab and brings her back to life. Curt must help Julie deal with her new existence as military agents and local gang members try to find them.

When a bumbling pair of employees at a medical supply warehouse accidentally release a deadly gas into the air, the vapors cause the dead to re-animate as they go on a rampage through Louisville, Kentucky seeking their favorite food, brains.