The world was a very different place when David Friend's book, Watching the World Change: The Stories Behind the Images of 9/11, came out, in 2006. The FSG title, which chronicles the stories behind 50 images that emerged on the day of the attacks, was re-released in 2011 on the 10th anniversary of September 11. Upon its re-release, Friend said, there was a sense that the book was "even more relevant." CNN agreed, and now a forthcoming documentary produced by the cable network, called The Flag, has enabled an unusual tie-in edition: a 99 cent single chapter e-short from Friend's paperback publisher, Picador.

"Twitter didn't exist during the attacks. The cell phone camera didn't exist, either," Friend noted. So, when the book re-emerged in 2011, fresh on the heels of the Arab Spring, Friend thinks that the "thesis of the book struck a deeper chord." Thinking there was an opportunity to do something new with the book, Friend reached out to the documentary filmmaker Michael Tucker, whom Friend had worked with when he was the editor of Friend floated the idea of turning the last chapter of his book, about an iconic shot of three firefighters raising an American flag, as the subject of a film.

Tucker, who liked the idea, brought it to CNN and the network picked it up for a new documentary production unit it had just established, CNN Films. Although production initially lagged, Friend said that, in the week following Hurricane Sandy the project saw renewed interest. "That week there was such a mobilization of people supporting one another, and we had that same feeling of the city coming together after another tragedy. [CNN] greenlit the film that week, I think, in part, because this flag-raising picture by three firefighters somehow brought a ray of hope amid the devastation and death."

Picador's e-short, which features new reporting from Friend, is being cross-promoted by CNN on a microsite for the documentary. Although the e-short is not the first from the Macmillan imprint, the publisher thinks it is unique. The exciting thing, a spokesperson said, is that Friend's chapter "offers a different, and likely as rewarding, experience as CNN’s documentary," while remaining "closely connected" to the film.

CNN's The Flag will debut on the network on September 4 at 9 pm EST.