Dean is a beast. If you are not a runner, he is the one who runs 200 miles at a time. He is the one who runs 140 miles in death valley - more than once. He is the one who is crazy enough to run 30 miles without training - in his mowing shoes! Crazy.
The book is basically about Dean and his crazy running regimen. The first half is mostly about Dean getting back into running after a long delay. He ran track/cross country in high school, but a shitty coach pissed him off so he stopped running dead in his tracks. 10 years later, he didn't like his life and decided to go for a run. 30 miles later, he decided to stop. That is when he decided to get serious about running. He goes on to run multiple ultras. Ultimately qualifying for the Western States 100.
The second half of the book focuses on his 200 mile run through California. This run was originally supposed to be a 12 man relay race, but instead Dean ran it on his own! It took over two days, he ate over 25,000 calories and he ultimately fell asleep while running, but he finished.