'Safety Not Guaranteed' Soundtrack: How Guster's Ryan Miller Made An Indie Score Worthy Of John Williams (AUDIO)

"Safety Not Guaranteed" isn't your typical indie romance. For starters, it's about the possibility of time travel: The film is loosely based on a 2005 classified ad-turned-internet meme posted by a man (played by Mark Duplass) looking for a time travel companion. 

"Wanted: Someone to go back in time with me. This is not a joke," reads the ad. "You'll get paid after we get back. Must bring your own weapons. Safety not guaranteed. I have only done this once before."

The plot isn't the only unusual thing about "Safety Not Guaranteed." The indie film's budget was small, but the score, which director Colin Trevorrow compares to one you might find in a blockbuster like "E.T." or "Superman," is full of big sound.

"There are some amazing indie scores, but usually the big themes go to movies that are budgeted at $100 million or more," Trevorrow told HuffPost Entertainment. "'Safety Not Guaranteed' is modeled almost after the 'Star Wars' score."

That's rare for an independent film -- and perhaps even moreso because of its source: Guster lead singer Ryan Miller, who wrote the score for "Safety Not Guaranteed."

"After I had worked on [the independent film] 'Nobody' as a goof, I kinda got the bug," Miller, who has spent the better part of 20 years touring with Guster, told HuffPost Entertainment about his transition to filmmaking. "I had an epiphany: This is what I want to do with my life. I felt the real power. It played to my strengths of melody and arrangement and I really like the working relationship with directors."

The only problem was getting the chance to prove himself. Thankfully, a mutual friend introduced him to Trevorrow.

"He was a Guster fan and the first night we met, we got drunk in Vermont," Miller recalled. "I was like, 'Hey, can I score your movie?' And he was like, 'I was going to ask you if you'd be interested in scoring a movie!' He didn't know if I'd ever done it before and I didn't know if he'd be amenable to it."

Miller's hunger played right into Trevorrow's hands.

"I think everyone involved in this film has a little something to prove," Trevorrow said. "Aubrey Plaza, Jake Johnson, Mark Duplass, Karan Soni, myself, Derek Connolly, the writer. When you bring together a group of people who are all are trying to demonstrate that they are more than what people think they are, you can get something inspired."

That's a theme of "Safety Not Guaranteed," which focuses on the ad's possibly crazy writer, Kenneth, and the reporters who track him down to suss out his story. Kenneth's relationship with Darius (played by Plaza, in her first starring role) makes up the bulk of the film, which goes in a direction that audiences might not anticipate -- something the score does as well.

"There's a head-fake in this movie," Miller said. "It starts off and feels like a quirky, indie, mumblecore thing that you've seen a thousand times before. But there was something about the score not giving away what was coming. The score unfolds and culminates in place that doesn't have anything to do with where you started."

It's a great trick, one made even more impressive because of the film's limited budget.

"It's amazing what Ryan was able to do with the resources we had," Trevorrow said. "He had to build from a couple of instruments in his recording studio to doubling, tripling and quadrupling them. We got a French horn because the violinist's girlfriend played French horn. It was that kind of thing."

Not that Trevorrow expected anything less. 

"I can't say it impressed me because I had this undying belief that Ryan was going to do something fantastic. And it's not just cause we're friends -- he has a melodic sense that is uniquely suited for film scoring."

He also has the right attitude for composing.

"The very first lesson I learned, in any composing, is you have to let go of your ego. If the director isn't getting what he wants, you're not doing your job," Miller said, likely to the delight of many of his future collaborators. "That's the part of the game that I got right away: I had no problem with that. It's what makes it fun."

LISTEN: "Safety Not Guaranteed" Soundtrack

Scenes From 'Safety Not Guaranteed'