 While in the Springfield Elementary library , Bart finds a book of black magic and gets attached to it . That night , when Lisa reminisces about the family ’ s dead cat , Snowball I , Bart suggests that he could use the book he found to resurrect Snowball . At the Springfield pet cemetery with Lisa , Bart utters an incantation from the book but accidentally reanimates corpses from the nearby human cemetery instead . The zombies terrorize Springfield , turning many people into zombies . Meanwhile , the Simpson family has barricaded all the doors and windows except for the back door , which Homer forgot to do . Several zombies break into the house : Homer sacrifices himself to give the others time to escape , but the zombies leave him when they realize he does not have enough brains for them to eat . Lisa realizes that the school library must have a book that can reverse the spell . 
