Andor, premiering on September 21, is the latest of Disney+'s Star Wars shows to reach back to the franchise's origins for its story material. By diving into the backstory of Cassian Andor, who was first introduced in Rogue One: A Star Wars Story, the new show implicitly acts as a prequel to A New Hope. After all, it is telling the story of how Cassian became the man who helped the Death Star plans reach Princess Leia.

Diego Luna reprises his role as Cassian in Andor, and he is joined by Genevieve O'Reilly as Mon Mothma. Though she first took on the role of Rebel Alliance leader in the 2016 blockbuster, the character dates back to Return of the Jedi (played by Caroline Blackiston). Since then, she has also appeared in animated form during Star Wars Rebels, but Andor will present her rise within the Rebellion.

Related: Andor Is Breaking A Star Wars Show CGI Trend - And That's A Relief

O'Reilly spoke to Screen Rant about what she learned from Mon Mothma's arc in Andor, how much she hopes to explore over the course of two seasons, and whether many Bothans really died to bring her the plans from Rogue One.

Mon Mothma in Star Wars: Andor

Screen Rant: I'm so excited to have Mon Mothma back. We typically see her as very poised, very commanding of the room type of woman. Are there any conversations you had about other areas of her life that you really wanted to dig into?

Genevieve O'Reilly: I was interested to learn about this woman. I was interested, and I was grateful [to] Tony Gilroy and to Disney for carving space for her within the story for us to learn about this woman. I think I've always been curious about her, ever since I watched that scene that Caroline Blakiston did in Return of the Jedi.

There's a very famous line in there that fans will often quote to me: "Many Bothans died to bring us this [information]." There's a pain at the center of that there, and I was always curious. What is that? What has that woman had to carry? What has been the cost of that leadership? What is it? What do you have to sacrifice? What do you lose to be that leader? And I think that's what we're looking to investigate and to develop during Andor.

Have you ever heard the theory—it's more of a joke—that Manny Bothans was actually the name of one man who died?

Genevieve O'Reilly: No. I love that! [Laughs] Oh my gosh. I'll never be able to say that same thing again. That's brilliant.

I'm sorry. Every time I say it, I'm like, "Manny Bothans. What a man." Has anything changed about your opinion or perception of her as a result of doing this series?

Genevieve O'Reilly: I have even more admiration and respect for the character than I did before, once we've been able to excavate her, and see what her life is really like. What it was like to be a senator and to be married from the age of 16; how you've had to navigate the Imperial construct, and what that means to your life and choices. How free are you? And how difficult is it as a woman to have a voice in that environment?

I feel terribly proud of her. I'm thrilled because, in a way, this is unlike anything I've done before. I kind of know where she ends up, right? I'm interested in her journey to get there, and already I feel deeply proud of her. I'm a big fan of hers as a woman.

You've embodied this character since 2005. Some people leave their characters at work, but is she somebody you spent a lot of time over the years thinking about?

Genevieve O'Reilly: In truth, not really, because I didn't know I would have this opportunity to come back to her. It's been such a surprise, and a real gift each time when they have rang and said, "Would you like to do this?" And, of course, I would like to do it.

But now, after spending so much time with her, I really want to stand up for her. I really want to shine a light on her. And I think what we're working to do in Andor will hopefully allow us to then see her, and to see those very small moments in those later films have weight behind her. Do you know what I mean? We're almost creating a foundation now for a woman that we will see later on. Gosh, it's exciting to be able to do that.

Andor Synopsis

Cassian Andor and Bix Caleen in Andor

Andor will explore a new perspective from the Star Wars galaxy, focusing on Cassian Andor’s journey to discover the difference he can make. The series brings forward the tale of the burgeoning rebellion against the Empire and how people and planets became involved. It’s an era filled with danger, deception and intrigue where Cassian will embark on the path that is destined to turn him into a rebel hero. 

Check out our other interviews with Andor stars Diego Luna, Adria Arjona, Kyle Soller and Denise Gough.

The first three episodes of Andor premiere September 21 on Disney+.