LOS ANGELES: The newest "Star Wars" television series will tell the story of a dark period in the life of future "Rogue One" hero Cassian Andor as he decides how far to go in his lifelong battle against oppressive forces, the star and creator said on Wednesday.

"Andor" will debut on Walt Disney Co's Disney+ streaming service on Sept. 21. The 12-episode series stars actor Diego Luna as the title character, a rebel who sacrificed himself for the greater good at the end of 2016 film "Rogue One."

Creator Tony Gilroy, speaking to reporters at a Television Critics Association event, said he drew on tidbits from the movie to craft a backstory for the character. In "Rogue One," Cassian mentions he has been fighting in the galaxy's ongoing revolution since he was 6 years old.

"At the end of the film he says 'Oh my God, if we don't go out and make this final effort, then all of the horrible things that I've done for the Rebellion will be for naught," Gilroy said. "So we know there's a very dark period."

The series begins five years before the events of "Rogue One," Gilroy said, and the first season will cover a year's time. Disney has already ordered a second season, which will cover the next four years leading up to the beginning of "Rogue One."

"Above anything, this is a show about regular people" living their daily lives, Gilroy said, but are forced to make epic decisions.

Luna said "Andor" would not be predictable even though audiences know that Cassian's story ends as a young man who gives his life for others.

"I'm going to challenge everything you think you know about Cassian," Luna said. "I'm going to tell you something you don't know about what triggers that."