Sometimes it takes an outsider to tell the inside story of 9/11.

A new independent movie by a Mexican filmmaker and starring a Rhode Island actor debuts in New York City this weekend adds a twist to the 9/11 story by digging into post-traumatic stress disorder to show the guilt felt by first responders and survivors.

“I Was There” is a fictional account of an FDNY fireman who succumbs to his fears on the day of the attacks.

Instead of climbing up the stairs to save lives, he runs away only to be buried in the rumble of the collapsed south tower. Rescued from underneath the fallen debris, he is hailed as a hero while his secret forces him into isolation where he numbs the pain with alcohol.

“Heroes are human too,” said director and co-writer Jorge Valdes-Iga, who pitched the film to firefighters before releasing it. “The reaction was mixed. Some felt that it was disrespectful while others thought it confronted the human side of being called a hero.”

“The intention was always to honor the firefighter and hopefully shine a light on the subjects that are not talked about,” said Valdes-Iga, whose film was shown at the 2016 Fiuggi Film Festival in Italy and the Rhode Island International Film Festival.

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The movie was shot with a small camera in and around Manhattan, including at the National September 11th Memorial and Museum. On the 11th anniversary James Lee, the actor who plays the distraught and tearful firefighter Gus Johnson, returns to Ground Zero for the first time since the attacks.

“Gus knew he wasn’t a hero. He panicked and ran down the stairs but a photojournalist takes his picture . . . Gus doesn’t face his truth until he puts down the bottle,” said Lee, who wrote the initial script.

Living in Hell’s Kitchen, Lee said he was inspired through his casual exchanges with firefighters at midtown’s Engine Co. 54, Ladder 4 and Battalion 9. The firehouse lost 15 members on 9/11.

A former U.S. Marshal and correction officer, Lee said he felt a Civil Service camaraderie with the firefighters. “I didn’t see them anymore” after Sept. 11.

“This is a hard story to tell especially if you are a New Yorker,” said John Feal, founder of the Feal Good Foundation, a nonprofit that lobbied for federal funds for health coverage for first responders, lower Manhattan residents, office workers and volunteers who worked on the pile.

“I saw this film and it punched me right in the face,” said Feal, a construction worker. “For the last 15 years we heard a lot of stories but this tells a real story about PTSD. It brought back my own struggles,” said Feal, who was treated for PTSD after he lost part of his left foot when a large piece of steel landed on it.

“I have seen a lot of holes in walls and open liquor bottles. Some of these people are suffering and are embarrassed,” Feal said.

“I Was There” will be screened at the Firehouse Space, a former firehouse in Williamsburg, Brooklyn, on Sunday at 7 p.m. Suggested donations will be given to the Feal Good Foundation.