Holly and Sam Culkins are step-sisters, but unlike cinderella's, they get along pretty well. Despite the fact of having different mothers, they hold on to each other, praying that the other's safe especially since a virus has spread all over the world resulting to the dominance of mindless, flesh-eating zombies which they call biters.
The two have been living on their own in Holly's secured house ever since their parents died. In order to survive, Holly's been training almost everyday by working out and killing biters one by one around their little home.
On some days, Holly would make a run to the mall to grab a few things in order to survive, but one terrible turn on her bicycle made things worse for her and for Sam whom she left at home.