He touches on various experiences that he had (running the Badwater Quad - which is the Badwater ultra - 135 miles - 4 times back to back), 24 hour races and setting world records during them, the Leadville 100 (which you read a lot about if you have read "Born to Run") but the largest portion of this book is focused on his run across America. That is 3,063 miles across all kinds of terrain.
A large portion (probably 3/4) of this book is dedicated to this race. Marshall decided that he wanted to do this, and break the world record doing it. With a lot of work, he found a partner in crime for the race, a team to help him with all of the logistics of running and help him with massage, supplies, and injuries, and there was even a team to film their adventure across the country for a documentary.
It follows each state that he runs through across the country, how many miles he has covered and has left to go, what day it is when he enters the state, etc. I enjoyed reading about all of his progress. I felt like he really set his mind to his goal (running across the country) and did whatever it took to get through it. He battled MANY injuries throughout the 52 days that it took him to get from San Francisco to New York City. But he dealt with each and every one with dignity even when there were questions of whether or not he could continue.
I found this youtube by the publisher:
An ultra is DEFINITELY on my bucket list. How about you?