As the title indicates the book provides an account of the 2013 Boston Marathon from the perspective of people who participated in the race. It was the first I read of the experiences of the people who were running that day.
It starts out at the beginning of race day and introduces the reader to a number of runners as they make their way from the start in Hopkinton to Boston. If you have not run Boston it gives you a good idea of what the experience would be like due to the way Hal Higdon describes the course and the crowds along the course.
Hal Higdon did a good job capturing the spirit of the day with this book. I would recommend picking up a copy if you want to learn more about what turned out to be a tragic day.