Forty years ago, Charlie Croughwell was living in Los Angeles, looking to start a career as a stuntman when he happened upon Universal Studios' set.
Thanks to a woman at the gate who let him slip through, he soon found himself on the back lot, where "Back to the Future" was being filmed.
As Croughwell headed toward Max Kleven, the assistant director who was in charge of stunts, Michael J. Fox came toward Kleven at the same time. The actor looked at Croughwell, noticing the dark hair and the same 5-foot-5 height and build.
"Oh, this is gonna be my stunt double?" Fox asked Kleven.
Kleven looked at Fox and then at Croughwell. "Yep," the AD replied.
When Fox walked away, Kleven had to make sure.
"You do do stunts?" Kleven asked Croughwell.
"Yes," Croughwell replied, as Kleven breathed a sigh of relief.
Thus began a 16-year relationship between Fox and his stunt double, Charlie Croughwell.
For years, the greatest piece of "Back to the Future" memorabilia Croughwell had was the hoverboard he and Fox used to make the scenes in the sequel, which debuted in theaters 35 years ago this Friday.
The item remained displayed in the same spot in his office for decades. But things change.
Turning 65 made Croughwell think more about what would happen to it when he was gone. And he saw hoverboards, none of which he says were used for the flying scenes, selling for hundreds of thousands of dollars.
Over the last 10 years, more than 10 hoverboards have sold, with the high mark being one that fetched $500,000 at Prop Store in 2021.
None of them compare to Croughwell's.
"This was the only hoverboard that was used for the flying scenes," Croughwell said. "It's the only one that someone would be able to stand on."
Included in the lot are the flying harnesses, which were used by both Croughwell and Fox, as well as a letter from Bob Gale, co-writer and co-producer of the famous movie trilogy.
Gale wrote the hoverboard "was definitely 'screen used' and, to my recollection, it is the only such plywood 'hero' hoverboard to actually be filmed hanging from the wire rig. It was used by both Michael J. Fox and by Charlie."
"There has never been a hoverboard like this," said longtime movie prop expert Joe Maddalena of Heritage Auctions, which will auction off the item Dec. 7. "We're already at $125,000, and it wouldn't surprise me if it went for a million dollars or more."
The hoverboard is signed by Ricky Dean Logan ("Data"), Dean Cundey (cinematographer), Neil Canton (producer), Michael Klastorin (unit publicist), and Fox, who Croughwell got to sign the piece three or four years ago.
"Charlie — You are a legend, Love, Mike," Fox wrote.
Croughwell, who says he still gets residuals of $20,000 to $30,000 a year from the films, says he will donate at least half of the proceeds to the Michael J. Fox Foundation for Parkinson's Research.
"For 16 years, I was responsible for protecting Mike, to make sure he wasn't hurt or killed," Croughwell said. "And now, since he has had Parkinson's, there's nothing I can do, and it absolutely kills me."
Darren Rovell is the founder of cllct.com and one of the country's leading reporters on the collectible market. He previously worked for ESPN, CNBC and The Action Network.