Christopher Reeve's children open up about their heroic father's life in new documentary Super/Man

The life of Christopher Reeve is being showcased on the big screen in the new eye-opening documentary Super/Man: The Christopher Reeve Story.

The documentary had its world premiere at the Sundance Film Festival in January, where it was acquired by Warner Bros. Discovery for $15 million.

Now the film will be released theatrically in a two-night special screening through Fathom Events, with the first night on September 21 and the second on September 25, what would have been Reeve's 72nd birthday.

The beloved Superman star's children - Matthew, 44, Alexandra, 40 and Will, 32 - speak about their father's life in a new interview with People.

They reveal that the actor's life is laid bare in this 'unflinching' documentary that reveals sides of their father most hadn't seen, before he passed from heart failure in 2004 at just 52.

The life of Christopher Reeve is being showcased on the big screen in the new eye-opening documentary Super/Man: The Christopher Reeve Story

The life of Christopher Reeve is being showcased on the big screen in the new eye-opening documentary Super/Man: The Christopher Reeve Story

The life of Christopher Reeve is being showcased on the big screen in the new eye-opening documentary Super/Man: The Christopher Reeve Story

The life of Christopher Reeve is being showcased on the big screen in the new eye-opening documentary Super/Man: The Christopher Reeve Story

They reveal that the actor's life is laid bare in this 'unflinching' documentary that reveals sides of their father most hadn't seen, before he passed from heart failure in 2004 at just 52

They reveal that the actor's life is laid bare in this 'unflinching' documentary that reveals sides of their father most hadn't seen, before he passed from heart failure in 2004 at just 52

Just a few years out of Julliard - where he studied alongside another future star, Robin Williams, Reeve landed the role of Superman with just a handful of credits to his name, catapulting him to global fame.

While he was famous for portraying a superhero on the big screen, he exuded heroism for the way he carried himself after a tragedy, when he was paralyzed from the neck down in 1995 after a horse riding accident.

'Heroism is so much more than superficial strength and a glossy image,' Will said of his father's legacy.

'It’s about integrity, showing up for your family, persevering through hard circumstances, and still having that joy for life. That was our dad,' he said.

The film gives a rare glimpse into his life behind-the-scenes, including his complicated relationship with his professor father and leaving his partner Gae Exton, who he shared his first two kids, Matthew and Alexandra, with.

'It’s a beautiful thing to be able to see the full picture of a person’s life,' says Alexandra, who now sits on the board of Christopher and Dana Reeve Foundation.

'There were high highs and low lows but also two deep true loves and [three] kids that together blended into this beautiful family,' she continued.

Reeve's oldest son Matthew had previously made two documentaries about his father, with footage from those films used in Super/Man.

Just a few years out of Julliard - where he studied alongside another future star, Robin Williams , Reeve landed the role of Superman with just a handful of credits to his name, catapulting him to global fame

Just a few years out of Julliard - where he studied alongside another future star, Robin Williams , Reeve landed the role of Superman with just a handful of credits to his name, catapulting him to global fame

Christopher Reeve as the iconic Superman

Christopher Reeve as the iconic Superman

While he was famous for portraying a superhero on the big screen, he exuded heroism for the way he carried himself after a tragedy, when he was paralyzed from the neck down in 1995 after a horse riding accident

While he was famous for portraying a superhero on the big screen, he exuded heroism for the way he carried himself after a tragedy, when he was paralyzed from the neck down in 1995 after a horse riding accident

'We intended to honor his story but not make it a sugarcoated puff piece,' Matthew insists, adding how important it was to see how difficult his life was after the accident on him, his family and his caregivers.

Reeve married actress and singer Dana Morosini in 1992, who gave birth to Reeve's youngest Will that year.

Will called his mother, 'maybe the most special person to ever grace this earth,' adding that she, 'had a unique combination of grace and beauty and compassion and grit and intelligence.

Will and his older siblings agreed that it was Dana who truly kept the family together after the tragic life-altering accident.

The film is directed by Ian Bonhôte and Peter Ettedgui, who said that they learned so much about how Reeve had changed mentally after the injury.

'Christopher learned what was important after that. It wasn’t about making a successful film or more roles. It was his family, and focusing on his close bonds,' Bonhôte said.

Alexandra adds that the 'true gift' of the tragic accident is all of the kids got more time to speak with their father

Alexandra adds that the 'true gift' of the tragic accident is all of the kids got more time to speak with their father

The youngest Reeve child Will said he has seen his older siblings Matthew and Alex, become, ' phenomenal parents ... with my mom and dad shining through them in the best way'

The youngest Reeve child Will said he has seen his older siblings Matthew and Alex, become, ' phenomenal parents ... with my mom and dad shining through them in the best way'

Alexandra adds that the 'true gift' of the tragic accident is all of the kids got more time to speak with their father.

'Our dad had a near-death experience, so he knew not to leave things unsaid. Because we suddenly weren’t doing physical activities, we had a lot more time to sit and have conversations hanging out in his office,' she said.

The youngest Reeve child Will said he has seen his older siblings Matthew and Alex, become, 'phenomenal parents ... with my mom and dad shining through them in the best way.'

'You show up for the people you love and give them everything you have because you don’t know how long you have with them. That’s something I took from my childhood and will carry for the rest of my life,' he said.