A good documentary captures a particular thing on film, and like trapping lightning in a bottle, unleashes onto the screen that thing captured to electrify the viewers. “Fightville”, by Michael Tucker and Petra Epperlein (“How to Fold a Flag”, “Gunnar Palace”), is one such documentary, and the lightning captured is the microcosm of grassroots mixed martial arts.

The camera rests upon the shoulders of four men: minor league promoter Gil Guillory, whose USA-MMA organization toils in the realm of dirt-floored rodeo halls and backwoods civic centers; Tim Credeur, the wise UFC veteran and fight trainer; Albert Stainbeck, the MMA aspirant; and Dustin Poirier, the up-and-comer with a future. Of course, any UFC acolyte with a moderately decent memory knows that earlier this year Poirier debuted in the Octagon with stellar results, so his eventual success in the film comes as no surprise (to us ardent fans, at least). But oh, what a journey undertaken!

For Guillory, we see the journey to be an endless trudge through a lower-level promoter’s usual obstacle course. Tickets must be sold so profits at least equal costs. Fighters must be found and matched up, and God forbid if a match-up falls through. And don’t count on that talented big ticket seller to always be the one putting asses in seats, because eventually, if he’s good, he’ll move on to big and better things.

Not much is spoken of Credeur’s UFC career. Instead, his role as coach to Stainbeck and Poirier casts him as the mindful patriarch, dispensing beatings in training that translate into wins for his students when they fight. In theory, at least. In reality, the fighters’ own lives get in the way – one student with a fight coming up hasn’t been coming to class, and the beatdown Credeur delivers to him, meant as a lesson to show the fighter that his absences have left him unprepared, results in flared tempers and anger.

Then there’s Stainbeck. Stainbeck has seen success as an amateur, so the transition to pro looms. We see him train hard, we see him sweat and bleed, and we even see him practice his staredown in the mirror (remember “A Clockwork Orange”? It’s clear Stainbeck does.). But alas, with an unemployed ex-stripper girlfriend at home, rent due and a part-time busboy gig failing to make ends meet, the cards are stacked against Stainbeck’s success.

Poirier, on the other hand, is aces when it comes to fighting in a cage, and the success he finds there permeates the hazards life puts before him outside. No longer pudgy, no longer in trouble with the law, and focused on honing himself into the best athlete possible, Fightville tracks his ascension as he armbars one foe and knocks out another.

If the MMA documentary classic “The Smashing Machine” provided us with a macro-level view of one of the world’s best fighting before thousands in Japan on the biggest stage the sport had to offer, Fightville gives us the “micro” of it all. But it’s intimate, and in that intimacy dwell the qualities that make the film compelling. Guillory? If you’ve been to any of the local shows in your area, you’ve come across a Guillory, striving to stay afloat. Credeur? He’s your local MMA coach, and maybe that busboy clearing the dishes from your table and that troubled kid you knew from high school are budding mixed martial artists of varying trajectory. These are real people that you very well could know. And therein lies Fightville’s success. The sharp editing, keen musical score and deftly-captured action is just the icing on the cake.

Catch Fightville on DVD next year, or when it airs on Showtime on a date to be announced. It is definitely worth checking out.