If the making of Rogue One had its own musical score, things would have gotten deadly quiet in September, followed by the low rumble of ominous drums and a shift into the minor key: Uncertainty lay ahead…

That’s when the composer for the Star Wars stand-alone movie, Oscar-winner Alexandre Desplat (The Grand Budapest Hotel, Argo), dropped out. The movie had undergone reshoots over the summer, and scheduling difficulties were cited by Lucasfilm as the official reason for the breakup.

Just three months before its release, this was a major upheaval.

But then, if this behind-the-scenes drama still had its own orchestral accompaniment, the thundering drums would quicken into a frenetic pulse. Plucky pizzicato strings would underscore the absurd one-month deadline the new composer faced.

The hero rising up to save the day: Michael Giacchino, another Oscar-winner for Pixar’s Up, whose other credits include the Star Trek reboots, Doctor Strange, Inside Out, and the TV series Lost.

Fans also know him for his swelling scores to the Medal of Honor and Call of Duty video games, and he’s a lifelong geek whose studio is stacked with memorabilia, collectibles, and action figures from comic book and sci-fi history. Next up for him: the music to Spider-Man: Homecoming.

In between Doctor Strange and Spidey, Giacchino was supposed to have a brief break. But instead, he found himself rushing into another galaxy. He just finished recording music for the Star Wars movie two weeks ago. In between sessions, he spoke to EW about the breakneck project.

To read more on Rogue One, pick up the new issue of Entertainment Weekly on stands now, or buy it here – and subscribe for more exclusive interviews and photos, only in EW.

ENTERTAINMENT WEEKLY: So you were a late addition to the Rogue One crew…

MICHAEL GIACCHINO: Yes, literally the last thing I expected I’d be doing this month would be this. I mean we were literally planning a vacation when I got the call asking if I could come and talk to them about it. At the time, it left me with literally four and a half weeks to write. So it was one of those decisions where you’re like, okay, well… And I was talking to my brother about it. He goes, “Oh, come on. You’ve been writing this score since you were 10! You can do this.”

Four weeks doesn’t seem like enough time.

It’s not really. But you work with the time you have. And I’m not a person that has a bunch of other composers working for me, so it’s just me sitting up here in this room doing it. But I’m pretty good at focusing and getting down to business. I saw the film and I really, really, really enjoyed it, so there was no lack of ideas or inspiration, that’s for sure. The only worry the whole time for me was just the schedule. But I mapped it out and I thought, okay, if I do this much a day and I get this done that will leave me time to go back and improve if I need to before having to orchestrate.

Can you explain why there was a hand-off from Alexandre?

I’ll tell you, I actually don’t know an awful lot about that. [The filmmakers] were like, “Do you want to know what happened?” And my response was, “You know what, when this is all over we can sit and talk and have a drink and you can tell me whatever you want. I’d love to hear the story. But for right now I feel like I’d rather just pretend nothing happened and everything is good and I’m just going to come onto this.” And they were like, “Fair enough, fair enough.” So honestly, I don’t know anything about it other than what was purportedly, you know, “schedule issues.”

Wouldn’t it have been useful to figure out what was working – or wasn’t a good fit?

With that amount of time left, I was like, “I don’t want to get wrapped up in any sort of gossip or figuring out what was wrong when all we really need to do right now is figure out how do we just get accomplished what we have to get accomplished?” That’s why I was saying I want to be left out of this, everybody. “Mommy, Daddy, stop fighting and let me just do the work!,” you know. [Laughs]

Did you listen to any of what he had already written?

I was like, “No, I don’t want to. I want nothing, nothing. Let’s just do it.” … I’ve been excited to see this movie very much for the past year or so. And I thought, “Oh wow, Alexandre will probably do a really cool score for that.” And I was honestly looking forward to just seeing that and [hearing] whatever he did. I had never – not even an idea – that I would ever be involved in it. It all happened so fast.

How did it happen? Walk me through …

I got a call one day. I was on a plane next day because I had two days left of Doctor Strange scoring to do in London. And the day after my last day of scoring with Doctor Strange, [Lucasfilm] said can you come out to Pinewood? So I went out to Pinewood Studios and I met with everyone. They showed me the movie. And literally I came home with the movie.

Was it just nonstop from there?

I spent the weekend with my kids and said, “You know what? The next four and a half weeks are going to be brutal. But Monday I’m going to start it,” and Monday I sat down and started it. And there it was: four and a half weeks later, we were scoring.

I know what a hardcore geek you are. Does it stay fun when you’re working under such pressure?

Aside from all that it was really fun to do. It was really fun to come in every morning and just look up at the screen and see Stormtroopers running around. And I thought, “This is pretty cool actually…” Part of me was stressing out about the timeline. But the other part of me was just like, “This is the greatest thing ever! This is so much fun!” So I really tried to just keep all the negativity, whatever, or be away from it, just so I could look at it and enjoy it. I wanted to make something that I would be happy with – even though I’m usually not happy with anything I do. [Laughs] But, you know, always at least to try and shoot for it.

When you spoke with director Gareth Edwards, Tony Gilroy, who was brought on for reshoots, and Lucasfilm president Kathleen Kennedy about the music, what specifically do they ask for? What are the conversations like?

What you actually end up talking about is just the emotions. The less you talk about music and the more you talk about emotions, the easier I can understand what I need to do. After seeing the film, I told them what I felt about the movie, what I felt it could use, and what it needed. And we were all on the same page about those things.

Without giving away plot, what were your impressions of it?

It is a film that is in many ways a really great World War II movie, and I loved that about it. But it also has this huge, huge heart at the center of it, and that was the one thing I just didn’t want to discount. Yes, it’s an action movie, and it’s a Star Wars film, and it has all the things that you would come to expect and love about that, but I didn’t want to forget that it was also an incredibly emotional movie as well. That was what really pulled me in. I love working on projects that have an emotional center to them – and not manufactured emotion either, even though, you know, [laughs] it’s a weird thing to say because literally that’s all we’re doing, manufacturing emotion.

And what emotions did it make you feel?

What I liked about this movie is it didn’t feel false to me. It felt real, and I was able to just draw upon those emotions, whether it be sadness, loneliness… All of those things wrap into what we’re doing within the score. That was important to both Gareth, and Tony, and Kathy as well.

Earlier in your career, you wrote intense military music as the score for Medal of Honor and Call of Duty video games. Are there similarities to those scores and what you wrote for Rogue One?

It’s fair to say there is a bit of that feeling in there, for sure. I mean I like to think that I probably have written more World War II music than anyone on the planet after all the Medal of Honors and Call of Duties. [Laughs] But, yeah, hopefully you get a sense of the adventure without losing sight of what’s really important in the film and story. Sometimes everything can just be blown over by bravado, and I was trying really hard not to do that. To use it when you need it, but to also remember that bravado is a dangerous thing.

What inspirations will we hear in the music?

It does borrow from traditions that both John [Williams] and George Lucas borrowed from when they made the original Star Wars, you know. George was looking at Flash Gordon, the old serials, and John was looking at [Gustav] Holst and different composers along the way to get a baseline for what he wanted to communicate. There is a wonderful musical language that John put together for the original films. I wanted to honor that vernacular but still do something new with it, something that was still me in a way.

Kathleen Kennedy says they’re trying to break from some of the traditional Star Wars tropes, like doing away with the opening crawl. Sounds like that applies to the music as well?

Kathy said that to me, too — “No one is asking you to do what was done before.” I feel it’s important to be me, but in this universe, we’re working within. That was sort of the challenge. It was never sort of, “Oh, you have to do this, this, and this.” It was always just: “Here are the emotions that we need to cover.”

Did you have a favorite theme?

I really enjoyed working with Jyn’s theme, and tying that into the movie, and having it slowly develop. And it’s sort of a very emotional sweeping thing, which was really nice to do. Now, I feel like there is this interesting sort of thing going on in film scoring where it’s all about restraint. And at times I totally agree with that, but at other times it’s just nice to unleash everything and just let 110 players go for it.

It’s tough to convey music in words, but is there anything you can describe about the elements in your Rogue One music? A teaser before we hear it?

I remember writing to Don Williams, my timpani player, who happens to be John’s brother, actually. And Don has played on everything I’ve ever done. We’ve worked together for years, and he’s just an amazing timpani player. And the timpani is usually something that, you know, that’s an accent here and there, and comes in when needed.

So, heavy on the kettledrums and percussion …

I texted him about a week before the [scoring] sessions and I said, “Don… there is an F-load of timpani in this movie! And it’s complicated and it’s hard.” And he was just like, “Let me at it.” I don’t know that I’ve written more timpani for a film than I have for this. He did an incredible job and it gives this great weight, this great anchor to a lot of the pieces. But it also helps in the more chaotic moments as well.

Are there any other instruments that also take a lead role?

I think that there is perhaps slightly more ethereal things at work in this film too. How you may use an electric guitar… or how you may use any synth additions… It’s a symphonic score but there are these little accents that we added in order to sort of deal with certain story elements in the film.

Did you incorporate many elements of John Williams’ score?

I think absolutely there are a couple of times when you want to hit upon something that was from the past. For me, even as a fan, it was about going, “Oh, this particular idea would be great if we did it here. I would want to see that if I were watching a Star Wars movie.” As a kid who grew up with John’s music and who was catapulted in this direction because of what he did, I had a very specific idea of what I wanted to use and how I wanted to use it. That being said, I’d say the score is 95 percent original but with little moments [of Williams’ classic score] here or there to accent. If I were sitting in that seat and I heard that, it would totally raise the hairs on my neck.

Did you get to do your take on the Imperial March?

[Laughs] Maaaaaaybe.

You don’t want to say?

Well, what’s the fun in knowing what’s there? You want to be surprised, right?

Can you describe the opening title theme? Do you use elements of his work there?

It’s done slightly differently here because it’s not one of the saga films, it’s not one of the trilogies. It’s sort of its own thing and the whole idea from the very beginning was these should be standalone movies. So it’s going to be a slightly different way to get things kicked off.

What do you want people to feel when that music starts?

I think you’ll feel at home.