John C. Reilly, who stole the show in the Apatow-produced Will Ferrell comedy Talladega Nights, is the star here. He plays, naturally, Dewey Cox, whose life went off-track as a child, when he accidentally killed his brother in a machete accident and was so traumatized that he lost his sense of smell in the process. Rejected by his father, he leaves home at 14, guitar in hand.

As a young man, Dewey sets his sights on musical stardom, which he achieves with his signature single “Walk Hard.” He then experiences many of the same trials and tribulations that often accompany fame. He has a rocky marriage to his wife Edith (Kristen Wiig), meets his songstress muse Darlene (Jenna Fischer) and marries her without divorcing Edith, gets hooked on a variety of drugs, goes to jail, and plans a comeback.

The movie also shows Dewey reinventing himself over the years. He transitions from Buddy Holly-esque rock-and-roll, to rockabilly, to punk, and even disco. One of the funniest sequences finds him in mid-60’s Bob Dylan mode, singing “deep” protest songs whose lyrics are indecipherable at best. These parts of Walk Hard are really clever because they’re so knowing about the ever-changing face of the music business. One of the best scenes finds Dewey running into the Beatles (featuring Jack Black as Paul McCartney, no less).

Walk Hard, directed by Jake Kasdan, is dead-on in its recreation of the different eras and their musical styles. Because the film is so accurate, the satire feels that much sharper. Wisely, the movie also avoids making too-direct references to the movies it’s spoofing. I’ve grown tired of pictures like Date Movie, Epic Movie and Scary Movie that seem content to simply mimic famous scenes from other pictures. This one pokes some fun at the conventions of the musical biopic genre instead, and that’s just a much more satisfying way to go because it actually has a perspective on the topic.

John C. Reilly is outstanding as Dewey Cox. Like Will Ferrell, Reilly has the ability to create a three-dimensional comic character and then disappear into it. He plays the role straight, never winking at the camera or letting us know that he’s in on the joke. And, most enjoyably, he’s credible as a rock star. The actor does his own vocals and manages to adapt to every style of music his character ventures into.

I laughed a lot at Walk Hard. Much of the humor is raunchy, but that’s part of the satire as well. After all, rock stars don’t always live squeaky clean lives. While I was laughing, I was also admiring the endless creativity the film has in satirizing its subject matter. While I think Walk Hard is worth seeing in the theater, I’m pretty sure it’s going to make a killer DVD. Several scenes used in the TV advertising didn’t make the final cut, so they will doubtlessly be extra features on the disc. Now that I’ll buy.

( 1/2 out of four)

Walk Hard: The Dewey Cox Story is rated R for sexual content, graphic nudity, drug use and language. The running time is 1 hour and 36 minutes.