It is a strange time for “Star Wars.” Quiet at movie theaters since the 2019 release of “The Rise of Skywalker,” the mighty science-fiction series has been carried forward by streaming shows like “The Mandalorian,” “The Book of Boba Fett” and “Obi-Wan Kenobi,” in which characters old and new mingle in adventures that occasionally fill in gaps in the franchise’s master narrative.

The latest “Star Wars” show, “Andor,” which makes its debut Sept. 21 on Disney+, adds to the sense of strangeness by not following this pattern. It traces the life of Cassian Andor, the Rebel spy played by Diego Luna, along the rough-and-tumble trajectory that will eventually lead him to the desperate act of espionage he helps carry out against the Galactic Empire in the 2016 film “Rogue One: A Star Wars Story.”

At least at its outset, “Andor” is a show that is less interested in lightsaber duels or gratuitous cameos than in the details of day-to-day life on distant planets — the byzantine bureaucracies needed to run the galaxy and the conflicts that arise in these organizations. It populates its world quickly with numerous characters who do not fall easily into black-and-white categorizations of good guy or bad guy, and it is planned to run a substantial (for a “Star Wars” series) 24 episodes over two seasons.

That “Andor” has the latitude to follow its own idiosyncratic muse is largely because of its creator, Tony Gilroy. Gilroy, 66, is the writer-director of thrillers like “Michael Clayton” and a screenwriter of several Jason Bourne movies including the fourth entry, “The Bourne Legacy,” which he directed. He was also a savior of sorts when “Rogue One” threatened to go wrong, helping to rewrite its script and reportedly overseeing reshoots and editing. (Gareth Edwards is officially credited as the film’s director; Gilroy shares screenwriting credit with Chris Weitz.)

“Andor” is another “Star Wars” entry in which Gilroy’s involvement went from peripheral to essential, and although the series returns to some characters and ideas from “Rogue One,” he sees it as more than just a prequel series.

“We’re building from scratch, really,” Gilroy said in a video interview in August. “It’s very bravely built to continually escalate — it starts off as a chamber piece, and then we just go orchestral.”

Gilroy spoke further about the making of “Andor,” what he has learned about “Star Wars” from these projects and why running a streaming TV series is like commanding an aircraft carrier. These are edited excerpts from that conversation.

How were you brought onto “Rogue One,” and what did you learn about “Star Wars” from that experience?

I’ll tiptoe around that a little bit. Before they started shooting, they were looking for some rewrites. My father [Frank D. Gilroy, the Pulitzer Prize-winning dramatist] was passing away at that time, and I had a limited amount of time to help them out. So I worked on it for about a month to try to retool it, and then I didn’t really think about it for many months. And then I came back and they had some issues that they had to address. It was all hands on deck for 10 months, putting it together. My learning curve on the “Star Wars” universe was very steep. [Laughs.] And when we finished, it was a very exciting ride and everybody was very euphoric about the possibilities of what you could do next.

What did you realize you could do with “Star Wars”?

It’s a host organism for anything, really. After “Rogue,” with all the endorphins that were in the air at that moment, I remember having a conversation with Kathy [the Lucasfilm president, Kathleen Kennedy], and she said, “We can do anything.” I would say, “What do you mean by anything? If I wanted to do ‘Inherit the Wind’ in ‘Star Wars,’ could I do that?” And my God, we could. We could do a hospital show in “Star Wars.” How many beings exist in that galaxy? All those plumbers and farmers and anesthesiologists, they all have lives. Is it a real place or is it some phony thing? If it’s a real place, we can do real things. Then it has the added advantage of an audience.

Several of the films you’re best known for are very human and decidedly earthbound. What appealed to you about a big, expensive science-fiction franchise?

The experience on the show is imaginatively maximalist of the highest order. It gets into character, behavior and plots that are as complicated and as real as anything I’ve ever done. It’s the opportunity to have this really huge canvas without a filter, and the buy-in is adhering to the canon, keeping the fan base — well, it’s hard to satisfy everybody.

That’s a real education in itself. The fan base, you look at it monolithically in the beginning, and as time goes by, you begin to realize that there’s Shiites and there’s Sunnis, it’s all over the place. But I am not writing down in this show; I’m writing at the very top of what I can do.

Your involvement with “Andor” was not a direct handoff from “Rogue One.” How did that come about?

When we finished “Rogue,” there was this moment where they thought all these things were possible. They had a few speed bumps with “Solo” and all the things that happened there, that interrupted stuff a little bit. [The Han Solo prequel, released in summer 2018 after a tumultuous production, was a box-office disappointment.] But when they came back, they said, “We want to do a show about Cassian Andor.” They commissioned a pilot, and Kathy was ambivalent about it and sent it to me.

What kinds of notes or suggestions did you give Lucasfilm about the pages you were sent at that time?

I found the memo from four years ago where I basically said: It’s Cassian and K-2SO storming the Citadel — I don’t think you can do that for 20 episodes. I wrote a whole manifesto in some manic blitz. I said, “This is the show you should do.” I sent it to Kathy and it was like, OK, well, we’re not doing that. They tried another [approach]. When that fell apart, they read this memo over again and suddenly what seemed insane, two years earlier, was starting to look good. That memo is the show we’re making.

[Asked to confirm the timeline and development process that Gilroy described, Kennedy said in a statement: “Tony Gilroy has given us the story ‘Star Wars’ has been looking for. Tony’s ability to construct gripping characters with edge of your seat tension and action is unsurpassed.”]

How would you describe your vision for the series?

When you meet this character in “Rogue One,” you have very few navigational points. He says he’s been in this fight since he was 6 years old. He kills a trusted source in the opening scene of the movie. His history is dark, and he gives his life — not eagerly but with fully open compassion — to save the galaxy. That’s a pretty fascinating person. How much can we see that person be built? In the first episode, he goes from just an absolute mess to his first step on the road to Damascus, which is to be a mercenary. By the time we get to the end of this first half, he will have been exposed to a number of reasons for the rebellion. The second half of the show will be about him being a revolutionary.

From what I have seen so far, there are no obvious efforts in “Andor” to include the marquee “Star Wars” characters or to mention their exploits. Was that a deliberate choice on your part?

Like I said, the galaxy is enormous. It would be like if you tried to tell the whole history of 20th-century England just through “The Crown.” “Oh, there’s only this royal family, these seven people, their lineage and who they’re [expletive] — that’s all that matters.” We will not be dealing with the royal family of “Star Wars.” When we have legacy characters return, or when we touch on things that are familiar, we don’t want to do it in a way that would be perceived as fan service. We want it to be protein.

Do you think about how your choices as a writer are going to land with an audience that really knows and has spent a lot of time thinking about this fantasy universe?

That part is really potent. Another reason to do it is, everything that comes off my desk gets shot. And it gets shot with some of the greatest actors on the planet, with a bunch of really great directors. I’ve worked just as hard every day for the last 40 years on everything, and probably 80 percent of the material that I’ve written — probably the best things I’ve ever written — has been thrown away over the years. This is not that. It’s 650 pages of shootable script for the first part, and I’m so in the zone. To be old — not old, but I’m. …

Seasoned?

I’m seasoned, yeah. [Laughs.] To find myself at the age I am, and it’s a good feeling to write — that’s an exciting thing.

All of the franchise’s energy seems to be in streaming TV right now, and how audiences receive “Andor” will probably have a big impact on where “Star Wars” goes or doesn’t go next. Do you feel that weight on your shoulders?

It’s nuts. It’s a huge gamble on their part. Everybody’s gambling. A lot of people are doing things for the first time now. I don’t know how to sell something that’s 12 hours long. You used to go out and sell a movie, and you knew how to do it: Here’s my movie, people watch it, you can talk about it. We can’t really have a complete conversation, you and I, about this show, until Thanksgiving. You’re going to have billion-dollar shows. These are aircraft carriers. I’m commanding an aircraft carrier; “Lord of the Rings” is an aircraft carrier. Some of them will sink and some will float. Will they keep building them? I think it’s inevitable that we’ll keep going.