“9/11: One Day in America” will chronicle the events of September 11, 2001 through gripping first-person narratives of the first responders and survivors who were there. The first trailer should prepare audiences for the first-hand accounts of what they’ll be seeing; it isn’t just hearing the screams and shouts of people on the ground or in the building but, at times, watching debris fall from inside the Trade Center itself. Each episode will focus on the different levels of heroism people resorted to during the event and boasts never-before-seen footage, including from apartments and streets just after the planes hit. Shot over three years, the documentary filmmakers interviewed 54 people in person for a total of 235 hours of material. Subjects include the first FDNY chief to arrive at the World Trade Center on the morning of September 11, a firefighter who escapes the North Tower just before it collapsed, paramedics first to the scene who recall their devastating encounters of searching for life in the rubble, and bystanders who share their rescue stories after being trapped inside the towers under mountains of concrete.

The series spans seven hours, with the first episode of the series running at feature length. The first episode premiered June 11 at the Tribeca Film Festival as an official selection. The series is also an official selection of AFI DOCS and Sheffield International Documentary Festival. The documentary was developed and executive produced by the Emmy Award-winning 72 Films (“Inside North Korea’s Dynasty”) and Emmy- and Academy Award-winning executive producers Dan Lindsay and T.J. Martin (“LA 92,” “Undefeated”). The series is directed by Daniel Bogado. “We all remember exactly where we were on Sept. 11, 2001. Amidst the tragedy, chaos and sadness, what we also remember are the incredible feats of heroism, selflessness and humanity on display that day,” said Courteney Monroe, president, National Geographic Content in a statement. “With this series, we aim to immortalize these stories and continue National Geographic’s legacy of authentic, powerful storytelling that provides deeper meaning around important historical events.” You can watch the full trailer below.

“9/11: One Day in America” premieres Sunday, August 29 on National Geographic. The series will air over four consecutive nights with limited commercial interruption. In addition, episodes will be made available the next day on Hulu. Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.