Sarah-Koenig-SERIALThere’s a long history of radio broadcasts and stage shows. Many of the earliest radio programs in the pre-television era were recorded before live audiences. Radio stars in turn became popular touring attractions. Even today, there are extensive touring schedules for largely public radio shows from “Prairie Home Companion” to “Wait! Wait! Don’t Tell Me.”

What’s odd about “Serial,” the live show that stopped in at Wolf Trap in Vienna, Va., Saturday night is that it is based on something that was never on the radio, but a podcast. It was, in fact, the most popular podcast in iTunes history, with up to 87 million downloads to date.

A spinoff of “This American Life,” “Serial” investigated one story of a teenage murder in Baltimore 15  years ago through the course of 12 episodes, all done in that chatty “This American Life” style, with scene setting indie style instrumentals in the background.

Though it came to no conclusion (unlike, say, the spectacular end of HBO’s similarly serialized and stylized crime documentary “Jinx: The Life and Deaths of Robert Durst”), “Serial” did manage to result in a court of appeals agreeing to hear new arguments.

It also created a huge, adoring audience for the true crime storytelling of the series, which helped make up the large audience at Wolf Trap.

Podcasts, because of the intimate nature of their distribution — right into the earbuds of each listener, or a companion on long car trips — create a deep kinship with its voices, creating the demand to see the reporter Sarah Koenig and her senior producer Julie Snyder in person.

But how would they turn “Serial” into a stage show? “All Things Considered” or “60 Minutes” never went on the road quite like this.

Would they reenact the recording of an episode, using a variety of clever sound effects? Get convicted murderer Adnan Syed up on Skype? Bring out a Mail Chimp musical number?

Actually, they didn’t have much stagecraft at all: A projection of various documents to start with, accompanied with sound bites (that didn’t work as planned because it wasn’t dark out yet at the outdoor venue). Otherwise, it was two stools and music stands, a couple of microphones and a laptop cued up to relevant snippets from the show.

It was like a book talk, actually: An hour presentation followed by Q&A. Koenig called it at one point “our speech.” But because they are both very smart and funny women, with a proven ability to hold an audience, it was a very appealing evening.

Surprisingly, there wasn’t much really said about the case itself, its ugly details and unusual characters, and underlying it all, the stark depiction of sad suburban ennui at the turn of the 21st century. It was assumed everyone there knew the podcast and the case; they never stopped to explain the details (it also so much for the converted they referred to “This American Life” creator Ira Glass only as Ira, and still everybody knew who they were talking about, and even applauded).

Mostly, it was about how they put the podcast together and got its tone, and how it became such a phenomenon, and how they reacted to that.

The news of the appearance is that they are working on two new seasons of “Serial” involving two different cases simultaneously (which made you wonder how they could have time to tour). The first of them is still expected late this year.

Koenig is still in touch with Syed (and talked to him yesterday as a matter of fact) and is seeing developments in the appeal like anyone else. She still maintains that, whether he did it or not, the prosecutors case against him was filled with holes.

And about that Mail Chimp ad, which became famous on its own for the person on the street who mispronounces its name, they proved that it wasn’t racist as some charged, since the recorded voice in question was that of “a 14-year-old Norwegian tourist in line for an iPhone 6.”

The long lines of questions were largely statements of praise and devotion (if they had a book they would have asked for it to be signed and requested a selfie). While there were some questions to the point (that got applauded by others) still others were left unanswered.

Such as: The podcast’s use of the music; the sometimes-off puttingly conversational, slangy tone that verged on vocal fry; the running commentary on whether the reporter believes what she’s hearing; the inclusion of offhand humor (“There’s a shrimp sale at The Crab Crib”) just for fun.

The third question, though, was about their reaction to the devastating “Serial” parody on “Saturday Night Live” (about the existence of Santa Claus). While Koenig said it proved they had succeeded on some pop culture level, she said “It hurt my heart” because her story involved real people.

She missed the point that she was the one who had turned this tough case into something removed from news reporting and into the consumable entertainment realm— something that now even took them on tours.