When fans of This American Life tune in for this weekend’s episode, they should be ready to hear something entirely new. The long-running radio sweetheart is launching a new podcast, helmed by executive producer and host Sarah Koenig and executive producer Julie Snyder. Instead of “each week we choose a theme and put together different kinds of stories on that theme,” each week, Serial will release an hour-long episode that tells the next installment in the story of a 1999 murder.

The first season will be 12 episodes long — they think.

“For us, that it’s a podcast is so liberating,” says Koenig. “We can tell it as long as we need to tell it, and we don’t have to worry about it.”

The Serial team is hoping this suspense will be addictive and help to turn This American Life listeners into Serial fans as well. In addition to airing the first episode during This American Life’s usual time slot, Serial will be reaching out to its audience via Facebook, Twitter, and email newsletter, plus the occasional on-air shoutout from TAL host Ira Glass.

Serial worked with an outside contractor to build its new website, where they’ll be posting features like an interactive timeline, documents related to the story, photos of the characters, and maps, as well as a blog with additional information. For now, there’s no Serial app, which everyone agreed was too expensive for what is still, essentially, an experiment.

Serial arrives after a year in which This American Life left longtime distributor PRI to become more independent and to partner with PRX, which, according to operations and production manager Emily Condon, “distributes This American Life to radio stations, and handles TAL’s download sales through iTunes and TAL’s apps” but has no relationship with Serial.

A new podcast seems like a natural expansion for This American Life, which is itself of course already one of the most popular podcasts in the world. “The listeners have been really great about supporting a lot of the things we’ve tried to do over the years, whether it’s live shows or the TV show or special events,” says Snyder. Indeed, Serial topped Apple podcast downloads before episode one was even out:

The top podcasts list is looking pretty nice! @serial @ThisAmerLife @waitwait @Radiolab @freakonomics @podcaststartup pic.twitter.com/W9uNOVEoqO

— Rich Orris (@rorris) September 29, 2014

What’s more, some think we’re in the midst of a podcast renaissance. Here’s an excerpt from a recent Fast Company story by Rebecca Greenfield called “The (Surprisingly Profitable) Rise of Podcast Networks”:

The StartUp guys aren’t alone in thinking there’s “massive” money to be made in podcasting of this ilk. In the last six months, three podcast networks have popped up, from established public radio players: Infinite Guest from American Public Media, SoundWorks from PRI, and Radiotopia from PRX. Meanwhile WNYC has added more podcasts to its roster of shows, which includes the beloved, and very popular, Radiolab. This American Life, the radio show, is now spawning a podcast called Serial. Online print media has also gotten the message: Slate has doubled its podcast output in the last two years.

So everyone’s listening to podcasts these days, and This American Life is riding that wave — right? Not exactly. For many, podcasting is still very much an undiscovered niche.

“I went to my cousin’s wedding last weekend, and I will definitely let you know the aunts and uncles in my family are not super familiar with podcasting,” says Snyder. “That became a little discouraging after a while. But as a result of that, we have now put together a very short video tutorial with Ira and his 85-year-old neighbor and fellow dog park colleague Mary. Mary is an avid podcast listener because her eyesight isn’t great and she needs something to do on all her doctor’s visits — she really had podcasting down. So Ira and Mary explain in their video how to listen to a podcast.” [Update: A correction via email from Ira Glass: “My neighbor Mary is 86. Turns 87 on Oct 18.”]

Though an ever-growing number of people (of all ages) are tuning into podcasts, the reality is that the audiences are still nearly always smaller than what a show like This American Life can reach on terrestrial radio. Though podcasts have been around for a while, the behavior isn’t as mainstream as it may feel to converts — though Snyder did point out that the technology is getting more usable, and that even car companies are installing podcasting software into dashboards now.

“It will be interesting, once we start podcasting more, if the audience feels different than the audience we have for This American Life right now,” Snyder says. “I’m not sure — it will certainly be much smaller.”

(Podcast audiences are actually a little hard to measure. It’s possible to know how many listeners are on-site and on SoundCloud, but other apps like iTunes don’t make that information available, and tracking server-side downloads is still tricky, according to Condon, who says the team is working on ways to refine available metrics.)

At Fast Company, Greenfield argues that, as podcast audiences grow, so do the potential profits for podcasters:

Podcast ads are unique. Unlike advertising on almost any other medium, people like the interruption, mid-program, to learn about Squarespace and Stamps.com. Often, hosts read the ads in the tone and style of the show…

“People really pay attention to the ads,” Slate’s podcasting guru Andy Bowers says. That’s partly because they have to: The hosts are often right in your ear, and there’s no quick way to change the station, like on a radio.

While Koenig and Snyder disagree with the idea that listeners enjoy being interrupted, some of that logic does apply. Serial’s launch is being sponsored by MailChimp, a frequent podcast advertiser; other ad slots are available in 15-second segments at the beginning and end of the show. Koenig will voice the post-roll ads, “the way Ira Glass does at the end of TAL,” Condon says. The hope is that Serial will become self-sustaining via advertising and, later on, listener donations — but for now they rely on This American Life’s budget. (All Serial staffers, including new hire Dana Chivvis, are employees of WBEZ Chicago Public Media, as are all This American Life employees.)

So, though podcasting may again be on the rise, Serial’s not in it for the money, at least not right now. But being a podcast rather than a radio show has definite perks. For one, the format is more flexible — the podcast makes it easier to do a show that’s based on a season, which can be a struggle for local programmers to work around.

“The benefit of podcasting, obviously, is there’s a lot of administrative overhead you don’t have to deal with,” says Snyder. “You can do it with a smaller budget and a smaller staff.”