Reply All, Gimlet’s popular podcast about internet culture, has been going since 2014, with 158 episodes to date. It has covered websites that let students anonymously troll each other; what happens when you have one of the most coveted Snapchat usernames on the internet; and the history of “incels”, among other topics. This week, however, Reply All released not only its best-ever episode, but perhaps the best-ever episode of any podcast, in the form of The Missing Hit.

The episode follows Tyler Gillett, a director who is plagued by a musical mystery: what became of a funky guitar song he used to listen to on the radio as a teen in Arizona, and which he can’t find any mention of, anywhere, on the internet (other than a mysterious forum that appears to have some of the song’s lyrics). The podcast’s hosts, PJ Vogt and Alex Goldman, explore a glut of avenues to try to work out what Gillett’s song could be, from enlisting a band to recreate the song from his (admittedly incredibly detailed) memories of it to speaking to Steven Page, the lead singer of Barenaked Ladies, whose hits the track appears to ape. “How on God’s green Earth can you have a hit radio song that actually just gets vaporised from history?” asks Vogt at the outset, bemused at their inability to merely plug the lyrics into Google.

Facebook Twitter Pinterest ‘How does a radio hit get vaporised from history?’ ... Reply All podcast hosts PJ Vogt and Alex Goldman Photograph: Gimlet media

The episode is all about solving Gillett’s mystery, then, which is a compelling one. How exactly does a piece of music seemingly disappear from public consciousness, bypassing the hive mind that is the internet? How does a song with an obnoxiously 90s feel (one critic pinpoints it as a creation of “1997 to 1999”) fade within two decades to an inaudible footnote? Is the mystery song, in fact, an amalgam of different tunes lodged in Gillett’s brain, which over time have come together to make one strangely specific creation? And, if he is correct about these disparate melodies and snatches of lyrics about ice-cream sundaes and Bettie Page being from one song, then how has it remained intact in his brain for so many years while others have forgotten about its existence? (“Is there a sparser bassline? It feels busy,” Gillett asks at one point, as they recreate the song in the studio.)

It is also about the power of memory, repetition and the kind of madness that an earworm can provoke. Vogt speaks openly about his obsessive-compulsive disorder and about how Gillett’s fixation on the song mirrored his own temporary obsessions. (“Sometimes, my brain just locks on to things that don’t matter at all, like things that are small and stupid. Like I was talking to somebody the other day about this sci-fi book I read as a kid … the rest of my day [I was] trying to remember the name of this book.”) Audio is the perfect medium to convey this sense of intense curiosity, as the same familiar flute line and U2-inspired chorus rings out again and again and again and again. The only way to halt the cycle, says Vogt, is to listen to the song. Which is, of course, the one thing he can’t do.

It is also a story about the emotions tied to those memories; Gillett is overwhelmed when he hears the song recreated in a studio; no longer a potential fiction, but a living, breathing thing that other people can enjoy (or possibly endure).

Without wanting to spoil the ending, The Missing Hit is an incredibly emotive piece of storytelling. Whether or not Gillett’s song is real (and that would be telling), it becomes real for him and the Reply All team. The people they speak to – each an expert in their field – offer their own theories, but they can’t quite compete with the end result. “It felt almost like he had found a hole in the world. Like a glitch,” says Vogt. Ultimately, though, it’s an episode about the glitches in all of us; about trying to connect mental bits and pieces, and hoping that someone, somewhere, gets it … even when Shazam draws a blank.

Reply All’s The Missing Hit is available on Spotify and Apple