The late Christopher Reeve's children open up to ET's Rachel Smith about honoring their parents in 'Super/Man: The Christopher Reeve Story,' in theaters for one day only on Sept. 21, followed by an encore performance on Sept. 25. Will, Alexandra and Matthew Reeve take Superman fans inside their father's triumphs and tragedies with new sitdown interviews and rare home movies. Christopher Reeve died at 52 years old in 2004, nearly a decade after a horseriding injury paralyzed him from the neck down. Their mother, Dana Reeve, died months later from lung cancer.