United for days after, divided for years since — story about how we can unite a nation, told through the voices of families who lost loved ones during the 9/11 attacks.

The United States of America was brutally attacked on September 11, 2001. In the days after the tragedy, our stunned nation was united, despite age, race, religion or gender. Years later, the ripple effects of the attacks find the country polarized and divided. How do we unite a divided America like the nation was directly following the 9/11 attacks?

The attacks on September 11th 2001, left 2,977 people murdered and thousands more injured. More than a decade later, Tim Oliver, an art director from Huntington, New York, walked into work at One World Trade Center in lower Manhattan for the first time. The 104-story glass-and-steel skyscraper is built close to where the Twin Towers once stood. The site is also the home of the 9/11 Memorial and Museum.

On his way to work each day, Tim walked past two giant, cube-shaped pools, the footprints of the Twin Towers. Each pool is one acre in size with man-made waterfalls. The names of nearly 3,000 victims (from the 9/11 attacks and the 1983 World Trade Center bombing) are inscribed on bronze plates, which are attached to the low protective walls of each pool.

Those daily walks inspired Oliver to write “Finding Fifteen,” a book portraying 15 victims of the attacks told through the memories of their families. Oliver randomly selected the names, wrote letters to the 15 families he chose and conducted more than 55 interviews. During the writing of the book, another idea become clear—Allow the victims’ families the opportunity to tell a larger story about America through a documentary.

In the hours, days and weeks after 9/11, families of victims were left confused, anxious and frustrated about the whereabouts of their loved ones but, despite overwhelming grief, they took comfort in the unity they felt throughout the nation. In the documentary, “Sky So Blue,” five of the 15 families in “Finding Fifteen” recall the events of that day, reflect back on the lives of their relatives and remember the national unity in the weeks after 9/11.

This tragedy united our nation for a short time, they families say, but now feel the country is deeply fearful, polarized and divided. During Oliver’s journey, a common theme emerged: To honor their loved ones, the families try to live lives without the fear that plagues American society. The families desperately want Americans to learn the lessons of 9/11: That when one of us is attacked, we are all attacked. That we need to remember that more unites us than divides us. Is there hope for America? They answer that question.

This documentary will follow Oliver as he interviews the families of five 9/11 victims on camera. He will also interview a mixture of politicians and intellectuals to gain their perspective. Using both the interviews and historical milestones, the documentary will explore the ripple effects of 9/11: Fear, disunity, anxiety and powerlessness has taken root in America. One has to wonder, “Have the terrorists won? Have they changed us?”

Oliver will ask the 9/11 families: “What unites us as a nation? We knew the answer on September 12th, the day after we were attacked. Do we know now? How can we get the united feeling back that we had in the aftermath of the horror in 2001?”

We will accompany Oliver as he speaks with the other victims—the post 9/11 veterans—and schools asking the youngest American citizens—the post 9/11 generation—the same question: “What unites us? What makes us Americans?”

Collectively, the families believe the solidarity we had as a nation just after these attacks has dissipated and that our nation is more polarized than ever. Ultimately the families would like to see America united again. This documentary will call to action our nation to unite, backed by families of victims of that tragic event.

The documentary “Sky So Blue” is an adaptation of the 2016 non-fiction book, “Finding Fifteen.” Author Timothy P. Oliver has more than 30 years of media experience. Tim is a former reporter, copy editor and designer for the following publications: The New York Times, Time Magazine, Detroit Free Press, Atlanta Journal-Constitution, Asbury Park Press, Gannet Westchester Newspapers.