The boy whose story is being told.

Daniel Radcliffe’s “Harry Potter” stunt double David Holmes is opening up about the on-set incident that changed his life forever.

Holmes, 42, made Radcliffe’s Potter fly in all eight of the smash-hit films until an accident on the set of “Deathly Hallows: Part 1” in 2010 left him paralyzed.

A trailer released Wednesday for HBO’s documentary “David Holmes: The Boy Who Lived” introduces Holmes as a teen gymnast who had “no concept of fear,” according to his parents, and landed the “best job in the world” as Radcliffe’s adventurous stand-in.

Radcliffe added that Holmes “seemed like a cool older brother” while filming the movies throughout his adolescence.

But that all changed when Holmes was involved in a stunt gone wrong that resulted in him instantly breaking his neck and spending six months in the hospital.

“This terrible thing happened to Dave, but I don’t want to talk as if his life is a tragedy,” Radcliffe says in the trailer. “The way his life has affected the lives of people around him means that it is the furthest thing from that imaginable.” 

One crew member in the trailer called the accident the “worst day in the film business that I’ve ever had.”

“As Daniel and [David’s] closest stunt colleagues rally to support David and his family in their moment of need, it is David’s extraordinary spirit of resilience that becomes their greatest source of strength and inspiration,” reads a synopsis for the documentary, which is executive produced by Radcliffe and Holmes.

It will include, “candid personal footage shot over the last decade, behind-the-scenes material from Holmes’ stunt work, scenes of his current life, and intimate interviews with David, Daniel Radcliffe, friends, family, and former crew” to provide a well-rounded look into the man behind Potter’s high-flying tricks.

“David Holmes: The Boy Who Lived” premieres on HBO on Nov. 15 at 9 p.m. EST and will stream on Max.