"Now, Muscle Shoals has got the Swampers / And they've been known to pick a song or two."

For nearly 40 years, people have heard Lynyrd Skynyrd sing those words in 'Sweet Home Alabama' and not known what they mean. A strong new documentary by Greg Camalier, 'Muscle Shoals,' looks at the musical history of the tiny northern Alabama town, which has birthed a staggering number of classic recordings inside its two studios.

Songwriter Rick Hall co-founded Florence Alabama Music Enterprises (FAME) in the late 1950s. By 1960, he was on his own and opened up FAME Studios in nearby Muscle Shoals. He formed a house band with some local musicians and had success early on with R&B hits by Arthur Alexander ('You Better Move On') and Jimmy Hughes ('Steal Away').

By the mid-'60s, the work Hall and his band -- Barry Beckett (piano), Jimmy Johnson (guitar), David Hood (bass) and Roger Hawkins (drums) -- with help from Spooner Oldham (organ) and horn players, were putting out attracted the attention of Jerry Wexler at Atlantic Records. After taking a FAME-cut song, 'When a Man Loves a Woman' by Percy Sledge, to the top the charts, Wexler began bringing Atlantic artists down to FAME to catch that same magic. This led to a string of hits, most notably by Wilson Pickett ('Land of 1000 Dances,' 'Funky Broadway), Etta James ('Tell Mama,' 'I'd Rather Go Blind') and Aretha Franklin ('I Never Loved a Man [The Way I Love You],' 'Respect') that turned Muscle Shoals into, after Memphis, the capital of southern soul.

The kicker is that the core group of musicians were all white, and nearly all of the African-American musicians who ventured down to rural Alabama expressed their doubts ... until they started to play. The racial difference never caused a problem inside the studio, but outside its walls people often looked askance at seeing blacks and whites together. It didn't help when longhaired Duane Allman showed up and pitched a tent in the parking lot -- because hippies weren't very popular in rural Alabama either.

A recurring theme throughout 'Muscle Shoals' is that Hall was a demanding taskmaster with a hot temper, which, by 1969, soured his relationship with Wexler and Atlantic. As Hall was securing a new deal with Capitol, Wexler, who had vowed to bury Hall, wooed Beckett, Johnson, Hood and Hawkins with a deal of their own. The four of them left to build the Muscle Shoals Sound Studio across town, where they would soon be dubbed "The Swampers" by Denny Cordell, Leon Russell's producer.

With Wexler's endorsement, the new studio thrived, with the Rolling Stones ('Sticky Fingers'), Paul Simon ('There Goes Rhymin' Simon') and Traffic among the many rock acts who recorded there. Hall, meanwhile, put together a new band. Although they had scores of country and pop hits, they mostly lacked the prestige of what his former employees were doing. The Osmonds' 'One Bad Apple' may have sold millions, but it's not 'Brown Sugar.'

So what made Muscle Shoals such a hotbed of music that two studios could thrive in such a small town? Nobody can really say. The movie suggests that it comes from the Tennessee River, quoting everyone from a descendant of a Yuchi Indian to Bono, who wisely notes that nearly every great music scene has water flowing through it -- from the Mersey to the Mississippi. This idea is driven home by Anthony Arendt's gorgeous cinematography, which captures the natural beauty of the region in rich, sumptuous colors.

Hall is the story's main character. Born into poverty, his family was torn apart when his little brother died at the age of three, which drove his mother into a life of prostitution. Just as his career was getting started, his wife was killed in a car accident. The tragedies fueled both his desire to succeed and his demons. With his deep-set eyes and unironic handlebar mustache, Hall, now in his early 80s, comes across as a joyless man -- even off-putting -- but fascinating nonetheless. His central presence keeps the film a little too serious; the bulk of the lightness comes when the talking stops and the music starts.

Director Camalier fleshes out the story with contributions from all of the surviving Swampers (Beckett died in 2009) and most of the musicians whose music is heard, including Franklin, Steve Winwood, Jimmy Cliff, Mick Jagger and Keith Richards. Pickett, who died in 2006, is represented through archival footage. Gregg Allman talks about his late brother's involvement.

But for all the drama in Hall's life, there's a surprising lack of an emotional center. A final scene filmed for the movie -- when the Swampers return to FAME and record a song with Alicia Keys -- brings the story full circle, but it's still unsatisfying. In a year filled with great rock documentaries, 'Muscle Shoals,' for all its strengths, doesn't live up to those high standards.

Even with its flaws, 'Muscle Shoals' is a story that needed to be told, and Camalier does it well. Beautifully shot, and with some of the greatest music ever coming out of a theater's big speakers, it deserves to be seen on the big screen. If it's not playing near you, it's available via On Demand and iTunes. Check the movie's website for more information.

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