For many people, Christopher Reeve remains the iconic movie Superman, thanks to his work in four big-screen blockbusters in the 1970s and ’80s. After his time as the Man of Steel was done, Reeve was paralyzed in a horse-riding accident, and then used his celebrity to became an outspoken advocate for a variety of cause, including stem cell research.

Reeve wrote several books about his life, but now his story is being told in a new documentary called Super/Man: The Christopher Reeve Story, which will be playing in theaters next month. The film, from Warner Bros. and DC Studios, details Reeve’s life before and after his accident, and includes interviews with his sons. You can see the trailer below.

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Here is the film’s official synopsis:

The story of Christopher Reeve is an astonishing rise from unknown actor to iconic movie star, and his definitive portrayal of Clark Kent/Superman set the benchmark for the superhero cinematic universes that dominate cinema today. Reeve portrayed the Man of Steel in four Superman films and played dozens of other roles that displayed his talent and range as an actor, before being injured in a near-fatal horse-riding accident in 1995 that left him paralyzed from the neck down. After becoming a quadriplegic, he became a charismatic leader and activist in the quest to find a cure for spinal cord injuries, as well as a passionate advocate for disability rights and care – all while continuing his career in cinema in front of and behind the camera and dedicating himself to his beloved family.

Super/Man: The Christopher Reeve Story will play in theaters on September 21 and 25 — which also happens to be Reeve’s birthday.