Requiem for Humanity (Last Days, #1)

Book One follows groups of survivors trying to make it in the new world against increasingly overwhelming odds. But things are changing. The zombies are evolving, becoming smarter, and regaining their former sentience. Humans, just barely managing to scrape by as it is - struggling to hold on to hope where there may no longer be any - will soon have to face a more horrifying and disheartening realization. This world belongs to the dead now. And there may soon be no place for the last remnants of the human race in the sprawling graveyard that the earth has become.