No offense to F. Scott Fitzgerald, but if recent Hollywood movies are any indication, there are, in fact, nothing but second acts in American lives. In “The Rocker,” a comedy opening in the city tomorrow, Act 1 of Robert “Fish” Fishman’s (Rainn Wilson) saga climaxes in 1986 at the Agora Ballroom in Cleveland, Ohio. Propelled by Fish’s googly-eyed, grouper-mouthed drum attack, local hair-band heroes Vesuvius whip the hometown crowd into a frenzy. Clearly (a couple of characters even say so in case you don’t pick it up on your own), Fish isn’t just the band’s drummer — he’s Vesuvius’s sweat-gushing heart and soul.

Backstage, the group’s manager breaks the good news: A major-label record deal is only a few pen strokes away. Then comes the bad news: The label president’s nephew is a drummer, needs a gig, and, well, Fish will land on his feet, right? Wrong.

Once the band dumped him, Vesuvius went on to multiplatinum album sales while Fish landed in an office chair for two decades, daydreaming of the very real slight that broke his spirit and the wholly imaginary vengeance he has never served cold, hot, or in between.

Rudely awakened from a revenge fantasy in the present day, Fish lashes out at a co-worker and loses his job, his girlfriend, and his apartment in the aftermath. But apparently neither the urge to rock nor the inability to make that urge pan out skips a generation. Fish exercises the closest available middle-age option to moving back home by moving in with his sister and her family, only to discover that his portly teenage nephew, Matt (Josh Gad), and his rock band, A.D.D., are short a drummer.

When Matt, Fish, and A.D.D.’s moody, pretty-boy singer-songwriter Curtis (Teddy Geiger) and Goth-lite bassist Ameila (Emma Stone) are forced to rehearse by Web cam linkup, fame beckons via inadvertent Internet exposure (literally: Fish rehearses in the nude). Before long, Fish is finally living his dream deferred and making up for lost time by rocking out and acting out on tour buses, in hotel rooms, and backstage in venues of increasing size.

If you’ve seen “School of Rock,” you’ll know what’s in store for Fish and company as they gig, gag, grow, and montage their way to an inevitable showdown with Vesuvius. And if you’ve winced through the icky, seemingly randomly generated pop-culture name-dropping in latter-day episodes of “Gilmore Girls,” you’ll know how far to lower your expectations. “The Rocker,” like “Gilmore Girls,” takes place in an alternate universe where MTV and the Rock and Roll Hall of Fame are relevant, and where a generalist, genre-free “rock” spirit covers all musical tastes, ambitions, and song styles.

This sort of lame non-take on an area of human endeavor that in real life is an inherently partisan subject to both its practitioners and its fans would be considerably easier to stomach if “The Rocker” were more than mildly funny. But despite a lengthy list of excellent stand-up comedians and small-screen comic actors such as Mr. Wilson, Will Arnett, Demetri Martin, Jon Glaser, Jane Lynch, and Fred Armisen on hand, the laughs are absent because someone forgot to write enough jokes. Peter Cattaneo’s uncompromisingly flat direction is on par with the film’s economical approach to humor. The fact that “The Rocker” bears three credited film editors suggests that the producers either undertook a major and unsuccessful last-ditch attempt to bring the funny in the cutting room, or trimmed a series of sword fights, oil-refinery fires, helicopter chases, and other action sequences at the last minute.

Outside of concert films and documentaries, rock ‘n’ roll movies almost never adequately harness the combination of creativity, stupidity, and abandon that continue to loosely unite (even if only by omission) 50 years of individual and idiosyncratic musical glory and folly. Fish’s constant, unctuously delivered, rigidly doctrinaire insistence that rock stardom is subject to an unending list of rules is the embarrassing antithesis of the personality-driven and frequently self-destructive ecstatic acts of creation that the film ineffectively struggles to personify.

The brief but prominent on-screen display of the video game Guitar Hero addresses this movie’s spirit much more directly and honestly than Fish’s endless, boorish lectures on “what rock ‘n’ roll is all about.” “The Rocker” is a celebration of the inalienable right to be a poser and a tribute to the sad fact that each generation’s formulaic mainstream approaches to popular music — and to middling big-screen comedy — are as soulless as the last’s.