Alex is alone in the mountains when the world changed irrevocably. The people she runs into after the mysterious, unnamed event are either nice and helpful, like Ellie - the little girl who begins to accompany her - and Tom - the military-trained young man who couldn't have shown up at a better time - or they want to eat her alive. The trio has to survive and figure out how to protect themselves in a newly hostile world.
The characters are well-developed throughout the series, and the primary antagonists - those people who want to eat other people - are a fresh new twist on the now-ubiquitous zombie trope.
Ashes is the first in a series, followed by Shadows and Monsters. If the summary and cover didn't give you the hint, this is a scary, suspenseful, gory, violent series that is not for the faint of heart. It's recommended for older teens and young adults.