“Star Wars” fans were introduced to the heroic Cassian Andor (Diego Luna) in the 2016 film “Rogue One: A Star Wars Story.” He was part of a ragtag group that managed to steal the plans for the Death Star and set in motion the events that unfold in “Star Wars: Episode IV: A New Hope.”

The film offered few clues into Andor’s life but the new Disney+ series, “Andor,” will help paint a portrait of him through two 12-episode seasons that take place five years before the events of “Rogue One.”

The initial three episodes will be available on the streaming service starting Sept. 21.

Actors often create a backstory for the character they are playing as a way of justifying or explaining their actions. In the case of playing Andor in “Rogue One,” Luna had to create a history for the character. He was surprised once he returned to the role for the new series how close he was in making up a past for his character to what the series will present.

Tony Gilroy, executive producer and creator of “Andor,” found small snapshots of Andor’s past in “Rogue One.” He calls them little moments of truth that reveal the character’s past.

“The pieces that we had for Cassian were that he’d been in the revolution since he was six years old. We know that at the end of the film, he says, ‘My God, if we don’t go out and make this final effort, then all of the things that I’ve done, all the horrible things that I’ve done for the rebellion, they’ll be for naught’,” Gilroy says. “So we know there’s a very dark period. We’ve seen his behavior all the way through.

“I just started to build from those. We fit into all of those very well, but we completely expand on what it was. And it felt very important, particularly for a story where you’re taking somebody on a five-year journey, to really, really be fully invested in their complete story, from origin and as we know in “Rogue” to the end.”

The Disney+ series reveals how Andor will go from a rogue to a rebel hero by focusing on everyday people whose lives are affected by the Empire. The series establishes in the first episode the reason Andor talks about the horrible things that he had done.

Luna is excited that “Andor” deals so much with regular people. He sees this approach as a way to address some very serious topics that reflect what is happening in the real world. He sees “Andor” having far more depth than a regular action series.

“The complexity of a show like this and the story that ‘Rogue One’ started is what makes this job so interesting. You can’t leave the grey areas out when you talk about a revolution,” Luna says. “There are so many layers. When you talk about people surviving, the judgement is different.

“We’ll get to explain that. And we’ll get to show you also a community. It’s quite unfair to call the show ‘Andor’ because this is about a community.”

That community is going to include characters who are both familiar and new to the “Star Wars” world. The series also stars Genevieve O’Reilly, Stellan Skarsgård, Forest Whitaker, Adria Arjona, Denise Gough, Kyle Soller, Fiona Shaw and Faye Marsay. 

One thing the cast and crew of “Andor” have had to face is that the audience knows the exact fate of Andor. The fact he is around five years later to get involved in the “Rogue One” exploits kills some of the tension when Andor gets into what looks like a deadly situation.

Gilroy jokes that in reality we are all living in a prequel where we know everyone is going to die. His more serious answer is that the audience has a broad tolerance when it comes to having knowledge of what is going to happen. That is why a movie can be watched multiple times and still be enjoyed despite already knowing the outcome.

Luna’s solution is to challenge everything the audience thinks they know about Andor.

“Everything [that] made sense when you were watching the film is now going to be challenged because I do have that in mind. I know where it ends, and I can be very creative about how to get there,” Luna says. “I think it triggers a different part of your creativity when you start backwards. As audience, not as an actor, as audience I tell you there’s nothing I like the most than going to see big shows about historical moments that I know happened.

“It celebrates, in a way, and it challenges audiences in a very special way. It’s like you know this is possible. You know someone is capable of this.  Well, I’m going to tell you something you don’t know about what triggered that and, to me, that is when storytelling becomes fascinating.”