Tim Minear, who served as executive producer of the Fox television series "Firefly" recently said that devoted fans of the show will discover treats about the show's characters in the upcoming "Serenity" feature film.

In an interview with Sci-Fi Wire promoting his upcoming CBS series, "The Inside," Minear said that fans of the cancelled Fox television series will love the new feature film being directed by creator Joss Whedon.

"Fans are certainly not going to sit there and be bored while they learn about these people," he said.

Minear said that he is particularly impressed by the new developments in the character of River, played by Summer Glau, who reveals extraordinary martial arts skills.

"She's amazing," Minear said. "And the way Joss shot it, you can tell it's her, with long, continuous takes, the camera moving around during a certain fight. And it's Summer. It's her!"

Other characters will take some surprising turns as well, Minear promised, saying that the developments are "shocking."

"Serenity" opens in theaters on Sept. 30.