When television networks resort to adapting books that haven’t even been written yet, it’s time to start looking for new source material. Luckily, salvation might be as close as their smartphones. As the supply of books and comics ripe for adaptation dwindles, TV producers are looking to podcasts for fresh material—and finding stories with audiences as loyal as any book club's inner circle.

Like books, podcasts prove that a story works, that listeners like it and will keep coming back to follow it. More importantly, podcasts can prove an idea's viability at a fraction of the cost of producing a TV pilot. “It’s essentially a prototype of a produced franchise,” says Chris Giliberti, the head of multi-platform efforts at podcast company Gimlet Media. “In Silicon Valley terms, this is an MVP.” And in the past year, TV producers have started to recognize podcasts' value. Amazon announced last fall that Gale Anne Hurd, who helped transform The Walking Dead from a beloved comics series into a beloved TV series, would be adapting the horror show Lore for the streaming service. ABC is already working on Zach Braff's Alex, Inc., an adaptation of tech industry podcast StartUp. And now, Mr. Robot creator Sam Esmail is adapting Gimlet's Homecoming for Amazon, starring Julia Roberts.

Homecoming, which premiered its second season Wednesday, is uniquely suited for TV adaptation. For one, the fictional thriller already has a cast of TV and movie veterans that includes Catherine Keener, David Schwimmer, Oscar Isaac, Amy Sedaris, David Cross, and Alia Shawkat. And for another, its plot sounds like something straight out of an HBO pitch meeting: It's about a military vet receiving experimental treatment for PTSD and the therapist who treats him. It also, much like the best of prestige TV, plays with its own medium.

“I thought, 'It’s gotta be audio and serialized—everything else is fair game,'” says Eli Horowitz, who wrote the series. “From there, we tweaked the form to fit the story, and the story evolved to fit the form.”

Unlike most audio fiction, Homecoming doesn’t rely only on the conceit of found footage to justify why the listener can hear a private conversation. Homecoming isn’t just voices and thumping footfalls: In cell phone calls, Colin (played by Schwimmer) is constantly preoccupied with navigating the Detroit airport and directing cab drivers; Heidi (played by Keener) has a bubbling aquarium in her therapy office; conversations are periodically interrupted by a singularly persistent bird.

For Horowitz, experimenting with form is familiar ground. As publisher of McSweeney’s, he co-wrote The Clock Without a Face, a treasure-hunt book that gave readers clues to the locations of 12 emeralds buried across the United States; along with Russell Quinn, he created three wonderfully odd digital book-games, including The Pickle Index, a story told through a fictional recipe-sharing app. So when it came time to make Homecoming, he just saw podcasting as a new medium to tweak. “I wanted to use the form as a tool, rather than a limitation,” says Horowitz. “Writing it as a podcast forced us into a real focus and compression, to trust the characters and conversation to create the action, instead of just describing it.”

The TV adaptation, of course, will allow for more literal depictions of the action, and another perspective on the fictional world. Exactly how Esmail will do that in his version, though, is still an open question. “For an audio drama to be good, it does need to be really conscious of the limitations of that particular medium,” says Horowitz. “It’s an open question how that will translate to television.”

If Homecoming and other audio stories translate well, then podcasting—full of dialogue and exposition, devoid of visual nuance—will provide an entirely new template for TV. And the possibility of adaptation will change podcasts as well. For audio producers, especially those without the resources of a network like Gimlet, scoring a TV adaptation can bring in the kind of cash that allows them to approach the story differently. “I wanted to get outside of the therapy room, but that’s hard to do when recording in your bedroom on two microphones,” says Lauren Shippen, writer and producer of sci-fi therapy podcast The Bright Sessions. Shippen produced the first season of the podcast with a couple hundred bucks and some enthusiastic friends; three seasons later, with a Patreon, sponsors, and a TV option, her characters have started to move beyond Dr. Bright’s couch, and Shippen is able to record episodes in a professional studio.

So far TV producers have just looked to already-established podcasts to find the next big thing. But if the upcoming adaptations go well, studios could use the podcast medium as a farm league for future series, using audio stories as a way to determine what audiences will enjoy. “The potential over the long-term is a business that could look a good bit like Marvel,” says Giliberti. “You’re originating worlds and stories in a low-cost, experimental format, and then transitioning high-potential prospects into higher-return formats.”

A multiverse that’s home to Zardulu, S-Town's John McLemore, and the gang from Night Vale? Sounds like it's time for podcasts to go primetime.

This story has been updated to reflect that Amazon will adapt Homecoming, starring Julia Roberts.