In the first book on this tragic event, 4:09:43, Hal Higdon, a contributing editor at Runner's World, tells the tale of the Boston Marathon bombings. The book's title refers to the numbers on the finish-line clock when the first bomb exploded.

In 4:09:43, Higdon views Boston 2013 through the eyes of those running the race. You will meet George, a runner from Athens, birthplace of the modern marathon, who at sunrise joins the eerie march of silent runners, all aimed at their appointments in Hopkinton, where the marathon starts. You will meet Michele, who at age 2 helped her mother hand water to runners, who first ran the marathon while a student at Wellesley College, and who decided to run Boston again mainly because her daughter Shannon was now a student at Boston University. You will meet Tracy, caught on Boylston Street between the two explosions, running for her life. You will meet Heather, a Canadian, who limped into the Medical Tent with bloody socks from blisters, soon to realize that worse things exist than losing a toenail.

In what may be a first, Hal Higdon used social media in writing 4:09:43. Sunday, not yet expecting what might happen the next day, Higdon posted a good-luck message on his popular Facebook page. "Perfect weather," the author predicted. "A 'no-excuses' day." Within minutes, runners in Boston responded. Neil suggested that he was "chilling before the carb-a-thon continues." Christy boasted from her hotel room: "Bring it!"

Then, the explosions on Monday! Like all runners, Higdon wondered whether marathoners would ever feel safe again. Beginning Tuesday, runners told him. They began blogging on the Internet, posting to his Facebook page, offering links to their stories, so very similar, but also so very different. Over the next several hours, days, and weeks, Higdon collected the tales of nearly 75 runners who were there, whose lives forever would be shadowed by the bombs on Boylston Street.

In 4:09:43, Higdon presents these stories, condensing and integrating them into a smooth-flowing narrative that begins with runners boarding the buses at Boston Common, continues with the wait at the Athletes' Village in Hopkinton, and flows through eight separate towns. The story does not end until the 23,000 participants encounter the terror on Boylston Street. "These are not 75 separate stories," says Higdon. "This is one story told as it might have been by a single runner with 75 pairs of eyes."

One warning about reading 4:09:43: You will cry. But you will laugh, too, because for most of those who covered the 26 miles 385 yards from Hopkinton to Boylston Street, this was a joyous journey, albeit one that ended in tragedy. This is a book as much about the race and the runners in the race as it is about a terrorist attack. In future years as people look back on the Boston Marathon bombings, 4:09:43 will be the book that everyone will need to have read.