Summary from Goodreads:
Under the bubbling hot springs and geysers of Yellowstone National Park is a super volcano. Most people don't know it's there. The caldera is so large it can only be seen from a plane or satellite. It just could be overdue for an eruption, which would change the landscape and climate of our planet. Ashfall is the story of Alex, a teenage boy left alone for the weekend while his parents visit relatives. When the Yellowstone super volcano erupts unexpectedly, Alex is determined to reach his parents. He must travel over a hundred miles in a landscape transformed by a foot of ash and the destruction of every modern convenience he has ever known, and through a new world in which disaster has brought both the best and worst in people desperate for food, water, and warmth. With a combination of nonstop action, a little romance, and very real science, this is a story that is difficult to stop reading and even more difficult to forget.
Ashfall is an entertaining dystopia/post-apocalyptic book. I'm a sucker for a male point of view and Alex doesn't disappoint as a narrator. He is real, gritty, 16, and has to go through so much in such a short amount of time. It was really interesting to watch his character transformation. Alex starts out as somewhat self-centered. He detaches from his family to play video games or just to be alone. When his parents leave to visit his uncle's farm, Alex finds himself alone in the ash wishing he was with them.
When Alex sets out to find his parents, he has to fight off desperate people, looters, criminals, etc. Alex doesn't get many breaks, but the ones he does get are life-saving. Dara and her mother take Alex in after they find him bleeding to death on their barn doorstep. They stitch him up, feed him, and let him rest there. A sweet romance forms between Dara and Alex, and they start relying on each other to survive.
Overall, Ashfall is a fast-paced, high-risk read. I've seen many documentaries on the super volcano under Yellowstone, so this book was quite terrifying in that it could actually happen.