Spoiler alert: Serial did not solve the mystery of whether Adnan Syed murdered Hae Min Lee. But it did provide a solution for another conundrum: how to offer listeners an active role in a medium that's inherently passive.

Because the podcast turned listeners into armchair gumshoes, everyone felt they were part of the show—and part of a community of listeners trying to crack the case. It made the show addictive in a way that everyone wants to replicate. "Podcast producers are all trying to figure out how to 'Serial-ize' something," says Ben Johnson, host of American Public Media's Marketplace Tech.

To "Serial-ize" a show doesn't just mean get it the kind of mass popularity Sarah Koenig's podcast got—it means building the kind of invested fan base that turns first-time listeners into evangelists for the medium, spawning message boards and #Mailkimp memes.

"Every other medium depends on fans performing their fandom," says Stephanie Foo, a producer at This American Life. "It's difficult to do that with audio, because most people aren't familiar with audio editing software." Providing a way for unfamiliar listeners to connect over a show can be a way for podcasts to reach listeners outside of their overwhelmingly homogenous base, like Game of Thrones fans winning non-fantasy-loving converts with funny Red Wedding macros.

And using the format of Johnson’s new show, Codebreaker, American Public Media—one of the largest public radio organizations in the world—is trying to do just that.

Asking the Big Question

Each week, Codebreaker approaches a different form of technology with the same question: Is it evil? This may seem simplistic, but that's the point. A deceptively simple question—one that we don't usually bother to consider—gives fans something for the discussion boards. (So do the secret codes buried in each episode, but more on that later.)

"The question felt silly at first, but it's based in real feelings we have about technology," says Johnson, who covers news on Marketplace Tech but wanted to go deeper on his new podcast. "Even if it is oversimplified, actually asking this question head-on allows us to look more closely at how tech changes our behavior."

The first episode, released on Nov. 11, tackles the morality of email. It can be irritating, sure, but you (and the Codebreaker team) would be hard-pressed to find someone who finds it evil. But as the featured technologies become more controversial—the second episode, released yesterday, is about Internet porn—Johnson promises that "you will absolutely hear people in later episodes come down steadfastly on one side or the other. And I won’t pretend that I don’t have opinions."

Besides, a firm pronouncement isn’t the point: the discussion is. Whether any of these technologies are evil or not, Johnson believes it’s necessary to thoughtfully consider the question. "We're not trying to indict any of these things—we’re trying to understand our relationship to them better," Johnson says.

Bingeing, for Your Ears

Codebreaker episodes are available for download every Wednesday. But they're also available in a delivery model new to podcasts: binge-listening. Each episode contains a buried code, which unlocks the next one. So, theoretically, you could solve all the codes and listen to the whole eight-episode season after only the first episode's release—a four-hour challenge that five listeners completed in the first 24 hours after the first episode was uploaded.

The puzzles provide a way for users to actively engage in the podcast, and form an online community around the episodes—like what happened with Serial. "We thought, how do you engage people with podcasts, and play along with them?" says Johnson, who says the Codebreaker format was inspired by Ready Player One and the season-wide Easter egg in Archer.

It's funny—tech people and puzzlers are all like, 'Yeah, the codes are too easy.' But a lot of other folks have said that the codes have been really hard. Codebreakers host Ben Johnson

"It's funny—tech people and puzzlers are all like, 'Yeah, the codes are too easy.' But a lot of other folks have said that the codes have been really hard," Johnson says. You can listen to the shows traditionally, too, as they come out each week—and the majority of *Codebreaker'*s listeners likely will. But as Johnson sees it, the codes can draw in listeners who don't already love podcasts, and give them a chance to build a community. So far, the strategy seems to be working, if slowly. There’s an active Subreddit giving hints for the codes for each of the episodes.

Unlocking the Echo Chamber

Radio networks, like American Public Media, usually respond to the need for more diverse listeners by varying content. "We're trying to have hosts that better reflect the makeup of the US," says Steve Nelson, program director of Infinite Guest, APM's podcast network. Infinite Guest has developed a number of shows featuring voices beyond the traditional well-educated, liberal, young, white, male host: This fall alone, they've launched The Mash-Up Americans, where two women of color tackle questions about race and ethnicity, and Unretirement, designed for baby boomers.

But podcasts don't usually reach out to new demographics by varying form. "There's a huge opportunity for people who are making this stuff to think more creatively than sitting down with a couple mics and a recorder and talking in a room," says Johnson. Codebreaker maintains that traditional podcast format—Johnson, who is white, talks to several individuals about their past experiences on each episode—but the distribution model is certainly a new experiment in giving fans a way to actively engage with the show.

So, to bring Johnson's question to his own show: Are podcasts evil? Well, they bring us tailored stories, which is good—but tailored for the overwhelmingly homogenous demographic that both creates and listens to them, which can be bad. Podcasts can be a platform for all voices, if the medium can find its way out of the echo chamber. Codebreaker experiments with format, which is a start. But its content mirrors the white-guys-around-a-studio-mic content that still fills a vast majority of podcasts. To crack the code and create podcasts for new demographics of listeners, there's still a lot to be done.