When a podcast is hailed on social media as “like Serial but better” and has already topped the iTunes charts within two weeks of its launch, it’s got to be worth a listen. In Missing Richard Simmons (First Look Media, Pineapple Street Media/iTunes), former Daily Show producer Dan Taberski appoints himself the search party for the eccentric celebrity personal trainer who disappeared three years ago.

Simmons’s short shorts, shock of curly hair and unconventional workout style made him the anti-Jane Fonda at a time – the 1980s – when celebrity trainers were booming. Acquaintances describe him as hilarious and foul mouthed. He was surprisingly accessible considering his level of fame, welcoming everyone to his Beverly Hills exercise studio for classes. There, he would invite them to dance with him and persuade men to take their shirts off. He wasn’t averse to flashing. Or baring his soul. His catchphrases, such as “sweat is just fat crying”, were well-known motivators.

Taberski admits he’s “not really an exercise guy”, but all that changed when he joined one of Simmons’s classes, which sound lively, to say the least. “It doesn’t take long for things to get weird,” he recalls. “Because in less than 30 minutes I find myself bare-chested, surrounded by step-clapping middle-aged women, as Richard wipes the sweat off my torso with my T-shirt and then shoves it down his shorts.”

But then, one February day in 2014, Simmons didn’t show up for a class. Regulars were shocked by his sudden disappearance: he didn’t return friends’ calls. Rumours flew that he’d been kidnapped or was living as a woman (both denied by his publicist).

As Taberski tracks down Simmons’s friends, he gets a sense of what an original he was, and you can understand why they are so desperate to find out what happened. “The goal isn’t to drag him back,” Taberski explains. “It’s to find out why someone like him would ditch the world.” At the end of the first episode, he leaves an impassioned appeal. “If you’re listening to this and you’re actually Richard Simmons, call me,” he says. “People are looking for you.”

No spoilers, but the mystery is one that’s likely to run and run. It’s just as well because each episode is half an hour of genuine warmth, intrigue and happy memories of who Simmons was. Or is. Who knows? The search continues.

If you like this, try this… Mystery Show