A blues prodigy at the age of five, Dewey Cox (John C. Reilly) blazed a trail through the music scene. Racking up number one hits left and right while fathering babies with multiple wives (Jenna Fischer and Kristen Wiig) and tending to his drug and zoo animal habits, Dewey's life has spun out of control. Working his way through the decades, Dewey searches for the elusive smash record, finding his time in jail or hosting a network variety show failing to jump start his creativity. Facing a life of failure, Dewey looks back on his years, hoping to heal his relationship with his disapproving father (Raymond J. Barry) or his older, considerably more beloved brother, whom Dewey accidently cut in half with a machete when they were kids.

"Walk Hard" is less thoughtful satire and creamy wit and more the distant cousin of "Airplane!" It's a slapstick pageant that puts recent lampoons to shame ("Epic Movie," "Date Movie," "Comebacks"), not just in laughs, but also in the specificity of the targets. It's not a wild take on pop culture softballs, but an extended riff on the likes of severely mediocre Oscar-bait such as "Walk the Line," with touches of "Ray" thrown in for good measure.

Surely "Walk the Line" needed a spanking like this, and the screenplay by Apatow and director Jake Kasdan whoops it up itemizing Dewey's naivety with drugs (he's easily duped into trying anything), his various dances with disaster, and his over-the-top rot of guilt. It's a fearless film, but not an easily controlled one. Kasdan, having spent his career with drier material ("Zero Effect," "The T.V. Set"), can't always lasso the best jokes out of a scene, and his tendency to let the gags boil over into complete point-at-the-camera obviousness grows old fast. This isn't his genre, but he's game to try. What "Walk Hard" lacks in a steady stream of belly laughs, it makes up for in pure screen oomph and an ache for extremity.

As with other Apatow films of late, "Walk Hard" is a cameo-heavy affair; the best has to be Dewey's interaction with The Beatles, as interpreted through Jason Schwartzman, Justin Long, Jack Black, and Paul Rudd, doing a dead-on John Lennon impression. The scene gives way to an LSD-inspired "Yellow Submarine" sequence that is easily the peak of craziness "Walk Hard" has to offer. Second on that list: extended male genitalia shots as Dewey experiences the sleepy aftermath of his first orgy.

"Walk Hard" also benefits from clever songwriting, with a swarm of parody tunes that offer the film a relaxed joke speed. With such tunes as the lascivious "Let's Duet" and Dewey's crossover smash "(Mama) You've Got to Love Your Negro Man," "Walk Hard" hits many of its highs with straightforward music montages, letting Reilly snatch the reins of the film with his agreeable voice and volcanic commitment to character.

"Walk Hard" comes at the audience from out of nowhere, and its lunacy takes some getting used to. This is a high-flying satire best met with an open attitude towards absurdity and a willingness to giggle.