Behind the Scenes of 'Independence Day: Resurgence'

— -- The aliens who invaded Earth in “Independence Day” are back 20 years later in the buzzed-about new movie “Independence Day: Resurgence.”

The movie reunites stars like Jeff Goldblum and Bill Pullman from the original film and also stars newcomers like Jessie Usher, who landed his role in an unlikely way.

Usher, 24, goes to the same gym as the movie’s producer, who one day mentioned the “Resurgence” project in passing, he told ABC News’ Nick Watt.

“I'm a huge Will Smith fan, and I was like, 'Oh, what? That's crazy! You should put me in that,’ and here we are,” said Usher, who plays the son of Smith’s original “Independence Day” character, Capt. Steven Hiller, in “Resurgence.”

Smith, 47, is not returning for “Resurgence,” which gave the movie’s director, Roland Emmerich, a new challenge.

“In a way it sort of forced me to have this new concept of a new generation, which got me really excited,” the German director, 60, said.

Emmerich, who shot some of the film in New Mexico, also revealed why he wanted to bring the “Independence Day” blockbuster back to the big screen.

“The technology has advanced so much,” he said. “I want to do another ‘Independence Day’ to show what I can really bring to the screen.”

“Independence Day: Resurgence” will open in theaters June 24.