Warning: Spoiler ahead

Philippe Petit became famous around the world for walking a high wire between the Twin Towers in 1974.

Robert Zemeckis' new movie “The Walk” depicts his incredible feat. And though Petit admits some things in the movie didn’t happen he confirms one of the most bizarre moments in the movie really did.

At the end when Petit (played by Joseph Gordon-Levitt) is about to get on the wire to begin his walk a man in a suit appears on the roof.

Petit and his accomplice are dumbfounded and stare right at him as the man stands looking at the horizon.

Philippe Petit at the top of the World Trade Towers in 1974. AP Then Petit and the man lock eyes. Petit grabs a metal pipe, just in case he has to fight off the man. The man nods and walks back into the building.

Petit told Business Insider that to this day he has no clue who the man was.

“That really happened and this guy could have made the whole thing collapse,” Petit said. “He could have grabbed me and called the cops. It was a miracle that he left and he came mysteriously.

Petit wrote about the mysterious visitor in his book “To Reach the Clouds: My High Wire Walk Between the Twin Towers” (which has since been retitled “The Walk”).

In it, Petit gives more detail about what he was thinking at that moment:

“Guided by a frighteningly unconscious impulse, I find myself walking toward the visitor. He keeps walking toward me. We are walking toward each other. Thirty feet. I keep walking. It is a duel. Twenty feet. I am looking at him in the eyes. My chin is up. I feel strong. I am no afraid. Ten feet. I keep walking. I have fire in my eyes. I’m invincible. My dream is invincible. I see a short metal pipe on the floor; I slow down and pick it up. I’m not brandishing it. I’m just… The man has stopped. He is no longer at me. He is admiring the site with calm assertion, as if he needs to communicate his desire to avoid confrontation. Has he felt an intangible electricity in the air, a portent of doom? The mysterious visitor — probably a businessman who works in the tower and wants to admire dawn before going to his desk — leaves my roof as he appeared, slowly and peacefully. I take it there will be no duel today. Except the one scheduled between the void and me, where it is written — I wrote it — “Both sides will survive.”

“The Walk” is now playing in theaters.