City of the Dead — Brian Keene

Where can you go when the dead are everywhere? Cities have become overrun with legions of the dead, all of them intent on destroying what's left of the living. Trapped inside a fortified skyscraper, a handful of survivors prepare to make their last stand against an unstoppable, undying enemy. With every hour their chances diminish and their numbers dwindle, while the numbers of the dead can only rise. Because sooner or later, everything dies. And then it comes back, ready to kill.