Kevin Clash is not a monster. He has simply lent his voice and movement to one for the past 20 years.

In Being Elmo, which opens next Friday, viewers get to meet the man behind one of Sesame Street’s most beloved furry creatures. And what a unique man he is, with an against-the-odds back story as a teenage outcast in Baltimore with a passion for puppets. But that all turned around when Clash got a local gig on a morning TV show, which led to him meeting the puppeteers in Jim Henson’s circle. Being Elmo footage captures this precious moment in time like a fly on the wall, but  it raises the question of how anybody knew to have a fly there. “That’s the question that everybody asks for every film festival we go to,” says Clash.

In fact, the film comes from a PBS-syndicated show called Big Blue Marble that aired in the ’70s. “We were very lucky that we got that footage, because there’s a lot in there about what I was doing at the age of 17,” he says.

Being Elmo is also full of little-known tidbits, like the fact that Elmo originally spoke like a caveman. “Two puppeteers only did a couple of shows before they stopped performing the character, so nobody really got to know Elmo,” says Clash.

“I had about five or six voices that I was comfortable with; and when I saw Elmo, that was the voice that I thought would be right for him.”