Who would have guessed that chopping your older brother in half with a machete at a young age could only be remedied by becoming…America’s heartthrob rock star? Meet rock star Dewey Cox (John C. Reilly), whose lifelong journey is presented in the comedic mock-documentary, Walk Hard: The Dewey Cox Story, opening nationwide on December 21. The film is the latest brainchild of producer and co-writer Judd Apatow, director and co-writer Jake Kasdan and producer Clayton Townsend, whose previous collective track records include Superbad, Knocked Up and The 40-Year Old Virgin. 

Cox’s rise to fame is pockmarked with plenty of musician clichés: cycles of drug abuse, prison and rehab, with breaks for some 411 women and, further, 22 kids and 14 step-kids and oh — can’t forget all those skeletons in the closet.

This past Wednesday night, Reilly, in character as Cox, kicked off his promotional tour, Cox Across America 2007, at Cleveland’s Rock and Roll Hall of Fame and Museum, singing tracks from the movie with his sultry voice.

“I heard Cleveland rocks. Is that true?” Cox’s voice oozed through the mic. “Tonight, Cleveland rocks with Cox,” he continued in response to huge cheers from the crowd. 

The set’s highlights included “Guilty as Charged,” “Darling” and “Beautiful Ride,” all original songs written for Walk Hard under the direction of composer Michael Andrews and music supervisors Manish Raval and Tom Wolfe. 

The film takes its audience from the late ’40s to the present time, rolling through rock ’n roll, hippie-dom, disco, the ’80s and more.

At age 14, despite his initial success at a local talent show, Cox’s father, Pa Cox (Raymond J. Barry) has little faith in him. In defiance, he leaves his tiny Springberry, AL home with his girlfriend, Edith (Kristen Wiig), to pursue his larger-than-life dreams of becoming a rock star. Soon after the couple marries, a slew of babies and bills begin to pile up, but Dewey forgets all about them in his rosy stupor of musical glory. Edith fails to be supportive, saying, “I do believe in you. I just believe you’ll fail.”

His big break comes when he is working as the only white man in an African-American jazz establishment. The headlining act’s usual lead singer is sick and unable to belt out tunes, so Cox steps his chubby self up to the plate and sings, “Mama, You Got to Love Your Negro Man.” Record executives help him land a chance of a lifetime. Cox records his first hit single, “Walk Hard” with his band, drummer Sam (Tim Meadows), guitarist Dave (Matt Besser) and bassist Theo (Chris Parnell). 

When he meets fiery redhead Darlene Madison (Jenna Fischer), whose power of attraction is second only to her piety, the two choose to remain “friends” despite several obvious sexual-esque encounters. The pair’s hit, “Let’s Duet” (let’s do it!) includes lyrics such as: “In my dreams, you’re blowing me / A kiss….” The couple finally marries — Cox has forgotten all about his current and first wife — and as they are about to consummate their marriage on a round bed à la Austin Powers, Edith walks in on the two. 

Alone again, Cox falls deeper and deeper into the drug pit, leading to his first prison-followed-by-requisite-rehab stint. Behind bars, he decides to change for the better, writing songs that will pioneer the future, standing up for minority groups. Cox sings, “Let me hold you, little man…I stand for the dyke…I stand for the retard.” 

But on a visit to India, he falls back into drugs, trying LSD for the first time with the Beatles. Paul McCartney (Jack Black), George Harrison (Justin Long), Ringo Starr (Jason Schwartzman) and John Lennon (Paul Rudd) show up in his trips with “absolutely terrible impressions of their respective Beatles — except for Justin Long who actually does a pretty good George Harrison,” said Kasdan. According to Kasdan, that’s where the humor lies — the Beatles, Elvis and Buddy Holly make appearances throughout the movie, all impersonated by ridiculous comedians who milk their characters for all they’re worth.

It also helps that the cast brings its own style to the cameras. Wiig, a regular on Saturday Night Live, employs some rather impressive facial expressions when angry at her husband, and Fischer, from The Office, is full of slapstick sexual humor.

Previously underscored as the supporting actor in hits such as Talladega Nights: The Ballad of Ricky Bobby and Chicago, Reilly has finally arrived in the spotlight in a hilarious piece that offers crowd-pleasers: crass humor, sexual content, graphic nudity and drug use. Watching him as Cox onstage solidified the idea that the entire cast and crew “treated Dewey Cox as if he really existed,” according to Reilly.

The actor’s musical background and talent shine through clearly in his role as a real-life guitarist. He played in “several bands over the years, both blues and rock. I grew up acting in musicals as a kid. When this movie came to me, it was at a perfect moment in my life — I was just getting back into music as a part of my creative life.”

Reilly, as Cox, told the Review, “Man, I’m the Fountainhead. I don’t need no ear plugs.” And in response to his drug use? “LSD…Now, I don’t do that stuff no more,” he laughed.

“He was right in there with us every day,” said Kasdan of Reilly’s involvement in songwriting.  Reilly himself worked on many of the songs, including “Mama, You Got to Love Your Negro Man,” which turns out to be Cox’s ticket into a massive recording contract.

“John is a dazzling and extraordinary talent and I can’t imagine a more perfect Cox. He was incredible. I have no complaints,” Kasdan said. “The combination of gifts that he’s got, this incredibly funny, sweet quality and this incredibly real emoting you get from him doing this part, even though the part is completely absurd…There’s only a small handful of guys in that category and when you add being able to sing like that, there’s practically no one [else].”

Just remember: “Don’t talk back to the Cox, son,” said Reilly, as Cox.