Over the past eighteen years, monumental literature has been published about 9/11, from Lawrence Wright’s The Looming Tower, which traced the rise of al-Qaeda, to The 9/11 Commission Report, the government’s definitive factual retrospective of the attacks. But one perspective has been missing up to this point—a 360-degree account of the day told through the voices of the people who experienced it.

Now, in The Only Plane in the Sky, award-winning journalist and bestselling historian Garrett Graff tells the story of the day as it was...