Trent Reznor and Atticus Ross, the composers for HBO’s hit series “Watchmen,” discussed how they built and moved across two time periods through music in Variety‘s Artisans presented by HBO.

The Emmy-nominated composers’ initial approach wasn’t creating music for a specific character or scene. They tried to understand and feel the impression they were getting from the world before they started composing.

“It’s more about trying to explore what the role of music’s gonna be and how we can articulate that, express that,” explained Reznor.

For scenes set in the present, Reznor tried to build a tone that would constantly build up the tension in the scenes. “The stuff set in present day was more synthetic-based,” he explained. “Lots of atonal drums going on in the background, became almost a walleye sound effect that worked as an underscore.”

Reznor went on to explain the music behind the violent police brutality scene in “This Extraordinary Being” episode. He said the team failed to license a 1940s pop song just a week before cutting and mixing the episode. Scrambling to reimagine a sound that would feel like it was from the past but still maintained the horror of what was happening in the moment, he spent the weekend writing a new piece. “It [worked] as a contained pop song of the era but also set against this imagery, have a double-meaning that make it even more of a goose-bumps, unsettling thing,” said Reznor.

Both composers are content with the multiple worlds they have built for the nine-episode series. “There’s no piece that was compromised by time,” said Ross. “There’s no moment of music in ‘Watchmen’ that I look and think ‘gosh, I wish we could’ve done that differently or better.'”

Watch the full video above.