The world we knew is gone. The world of commerce and frivolous necessity has been replaced by a world of survival and responsibility. An epidemic of apocalyptic proportions has swept the globe, causing the dead to rise and feed on the living. In a matter of months society has crumbled: no government, no grocery stores, no mail delivery, no cable TV. In a world ruled by the dead, the survivors are forced to finally start living.
As the survivors settle into their prison home something has drawn them out into the open... out of the prison... out of their sanctuary. This is a major turning point for the overall story of The Walking Dead, setting the stage for years to come.