The trailer for a new documentary about “Superman” star Christopher Reeve includes an emotional moment from his son.

“Super/Man: The Christopher Reeve Story” explores Reeve’s career and activism after a 1995 equestrian competition accident left him paralyzed. The actor died in 2004 of heart failure at age 52,

In the trailer, his eldest son, Matthew, is visibly moved when he shares a memory of his father.

“We said goodbye, he gave this wave,” Matthew Reeve recalls in the preview. “That was the last time I saw him on his feet.”

The elder Reeve was an avid and experienced horseman. He was thrown forward after his horse balked at a rail jump in the Virginia event that caused his injury and paralysis.

The documentary features the actor’s own words, as well as intimate interviews with Reeve’s wife, Dana, who died in 2006 of lung cancer, and close friends Susan Sarandon and Glenn Close.

“Super/Man: The Christopher Reeve Story” is being released by Warner Bros. Pictures which is owned by CNN’s parent company.

The documentary debuted at the Sundance Film Festival in January and will be in select theaters September 21 and September 25.