When a documentary gets made, as an off-ramp passion project, by a noted filmmaker who normally directs fiction films, there’s a special curiosity and excitement to seeing the angle — and the kind of craft — he’s going to bring to it. “Jerry Lee Lewis: Trouble in Mind” is the first movie directed by Ethan Coen all by himself. Ethan, of course, has always stood a bit in the shadow of his older brother Joel (who for a long time took lone directing credit on the Coen brothers’ films, even though they were complex collaborations). So though it’s “just” a music documentary, this is Ethan’s chance to strut his solo stuff. And he does, in a very Ethan Coen way: clever, modest, borderline invisible, but with a kick that sneaks up on you.

“Jerry Lee Lewis: Trouble in Mind” is only 73 minutes long, and it tells the story of the great wild man of rock ‘n’ roll using almost nothing but old TV footage — performances that stretch back over six decades — and interviews that were also done primarily for television, often times on famous talk shows of the ’70s and ’80s. A lot of documentaries, especially these days, can wow you with the density of archival footage that gets poured into them: the home movies, the photographs and diaries and scrapbooks, the visual history and detailed private lives made public. “Jerry Lee Lewis: Trouble in Mind” isn’t that kind of movie. At times, you practically expect it to contain a credit that reads, “Chief Researcher: some dude combing through clips on YouTube.”

Ethan Coen, in other words, didn’t go out and interview a bunch of folks who told him insightful stories about Jerry Lee Lewis. It’s all anecdotes told mostly by Jerry Lee, very little of it “original.” You could say that’s an easy, or maybe even lazy, way to make a documentary. Yet sometimes it’s a relief to be liberated from talking heads. Ethan Coen is such a good filmmaker, and working with the ace editor Tricia Anne Cooke he combines the clips with so much taste and pizzazz, that the film delivers just what you want. It gets you high on Jerry Lee Lewis and keeps you there.

A celebrated filmmaker can approach making a documentary with a certain prerogative, and Coen exercises that by letting the clips play on as long as he wants, often for an entire song. Most documentarians wouldn’t do that — they’d give you a 20-second taste of Jerry Lee on “The Steve Allen Show” in 1957 singing “Whole Lotta Shakin’ Going On,” his slicked-back honey-blond hair leaping up like lava from a volcano, and then it would be time to jump to another piece of aural-visual information. But Coen seems to be saying, “How can you cut away from this shit? It’s too awesome.” And he’s right. Leave it to others to make the “American Masters” version of “The Jerry Lee Lewis Story.” Coen syncs the movie to his own pleasure centers — and ours. The result is that “Trouble in Mind” plays like an undiluted shot of rock ‘n’ roll moonshine joy.

The film is also laced with fascinatingly offbeat choices. It opens with one of those extended song clips: Jerry Lee on “The Ed Sullivan Show” in the late ’60s singing a country ballad about the heartbreak of being left by a woman. Why kick off the movie with country? Lewis, after hitting it big in the mid-’50s in tandem with Elvis Presley and Little Richard, had two explosively huge singles, “Whole Lotta Shakin’” and “Great Balls of Fire” (his biggest hit), both of which sold hundreds of thousands of copies a day. But the most infamous event of his career — the fact that he married his 13-year-old cousin, Myra Gale Brown — went public in May 1958, and it was such a scandal that it instantly and permanently squashed Lewis’s run as a youth-culture celebrity.

As he explains in an interview, he was forced to go on the road from city to city, working more than 300 nights a year, and it stayed that way for 10 years. In a flash, he had gone from making $10,000 a night to $200 a night. He was only able to come back, in the late ’60s, as a country musician, and in that regard country music became nearly as defining of who he was and is. (In the space of a few years, he’d amassed 14 country hit singles.)

Lewis was able to stage that comeback because a country boy is who he always was, even more so than Elvis, who for all his poor Southern roots had a brash cosmopolitan polish. From the get-go, Jerry Lee Lewis was an unvarnished hillbilly, and you see it right from the ’50s, when he looked like a backwoods hellion, with those squinty eyes and that small puckered mouth. Elvis, of course, had the moves, and they were instinctive but also stylized — his ebullient white-boy version of what he’d experienced in R&B clubs and gospel tent shows. Jerry Lee went to those same clubs, notably Haney’s Big House. And when he got famous, banging away on the piano, sometimes with a stiff-armed staccato that was like a parody of piano playing, then kicking the stool away as if it were the last vestige of civilization, his voice all yelps and whoops and baying-at-the-moon bravado, it was Jerry Lee who was the true hound dog.

The movie is built around the music, yet little by little, in a clip here and a clip there, Jerry Lee’s story gets told. We learn that the day he married Myra Gale, she was actually 12, and turned 13 the next day, a fact Lewis reveals without a shred of apology or shame. If there’s any incident that could have used more of the old-school deep-dive approach, it’s this one, but Coen wants to cue us to Jerry Lee’s attitude about it — that he didn’t blink an eye over the fallout, and never thought it was wrong to marry his child bride, and will make no apology for it now. He did it his way. Still alive at 86 (which many don’t realize, since all the other formative rockers are gone), Lewis has now had seven wives, and many reckless years on drugs and alcohol. At one point he recalls drinking two fifths of whiskey a day and getting “sober” to perform at shows by drinking a fifth of Tequila.

His looks got snaky, as we see him turn, over the decades, from a rock ‘n’ roll star who was almost otherworldly in his hair-flying ecstatic gleam to a sometimes courtly, sometime angry middle-aged redneck, the hair turning to copper coils. He had the aura of the preacher he might have been, but Lewis, like his cousin Jimmy Swaggart, would have been one corrupt holy roller. That’s why he became the Killer.

The film does include one amazing archival scrap: We hear an audiotape from the ’50s of Jerry Lee in the studio talking about rock ‘n’ roll with Sam Phillips, and Phillips is saying that the music lifts you up, but Jerry Lee insists that it really is the devil’s music. We know that the moralizing scolds of the ’50s felt that way, but it’s startling to consider how deeply Jerry Lee did too — that he was a sinner who loved to sin, who got off on the demons inside, yet once he was offstage they frightened him. As he explains in a later interview, he’s a Pentecostal soul who doesn’t use the word “religion” because the Bible doesn’t either; he uses the word “salvation.” That’s what Jerry Lee Lewis believed in: that you were going to heaven or hell. In “Trouble in Mind,” we connect with the spirit that moved him — the feeling that he, perhaps, was destined to be in both places at the same time.