There’s no earthly explanation for why a band as explosive as the Sonics ever happened. Seattle-born director Jordan Albertsen tells the story in his new movie, “Boom: A Film About the Sonics.” Now on a limited run of just 15 cities, it shows at the Regent in Arlington on Sept. 18.

Spawned in Tacoma, WA in the early ‘60s, the Sonics were the definitive garage-rock band and the forefathers of punk. The very titles of their songs — “The Witch,” “Strychnine,” “Psycho” — were enough to scare away the unhip. After leading straight lives for decades, the core members were induced to reunite for New York’s Cavestomp festival in 2007. This led to years of steady touring and they hit Boston twice in 2015, including the Leader Bank Pavilion (then called the Blue Hills Bank Pavilion) at the behest of headliner Robert Plant.

Albertsen began his work 15 years ago while the band was on the road; it was his own dad that turned him onto the Sonics, “It became a personal thing for me to do this for the band, to give it to them. If you know these guys, they still don’t seem to fully understand how important they were, even now they’re still bewildered by it. And they were confused why anyone would make a movie about them; I think they thought I was crazy.’ I remember one of them saying, ‘Why don’t you make a movie on the Rolling Stones? Nobody knows who the hell we are.’ I said “That’s the whole point’. After awhile they said ‘We better give this kid some access or he’s never going to leave us alone’.”

The film traces the band’s roots to the party scene in Tacoma, a gritty industrial city not unlike Liverpool, which liked its music raw. “There was just some magic when the five of those guys got together — that mixed with (producer and mentor) Buck Ormsby not wanting to spend any money on a fancy studio, and having  them bang the stuff out as loud as they could.” Though it doesn’t get into all the bands the Sonics influenced, ,the movie does give a nod to Boston’s Lyres, who were covering Sonics tunes before it was cool. “I know there were a lot of garage scenes but the film also kept circling back to the Midwest.”

When the movie seemed about to fall apart, one influential Sonics fan came to the rescue. “I was working at a sushi restaurant in Montana, and all of a sudden (Pearl Jam guitarist) Mike McCready and his family came in. I told him I was making the movie and that I’d been trying to reach him for ten years — and he sat down and said, ‘I’m in. Who else are you trying to get in touch with?’ He pulled out his cell phone, and that gave me the energy to continue on.” McCready helped pull in the other Seattle luminaries who appear onscreen, including members of Heart and Soundgarden.

All five original Sonics are still alive and most were present at the film’s recent Seattle premiere, but health issues will likely prevent them from playing together again (original sax player Rob Lind leads the current version). “Knowing what I know, I’d say the movie is a good swan song for the band — but if it’s not, I’ll be right there upfront. I can say one thing: We were incredibly lucky for that reunion that did take place.”