Those who’ve ever seen Punk’d can attest to the improvisational comedy skills of Dax Shepard, who put both himbo bewilderment and mock outrage to good use for Ashton Kutcher’s hidden-camera show, which eventually launched him into costarring roles in proper big screen entertainment like Without a Paddle, Employee of the Month and Idiocracy. Shepard’s latest film finds him chafed by the constraints of comedy, however, and working to try to break out of the box into which he feels he’s been put by Hollywood. A low-budget, long-on-the-shelf, industry-satirizing mockumentary in which Shepard recruits a pal to help him mount a self-financed, Chuck Norris-type martial arts flick, Brother’s Justice meets with some mixed early success before eventually crumbling due to a lack of focus.

With supporting appearances by Tom Arnold, Jon Favreau and Kutcher, Brother’s Justice has considerable heart, pluck and amiable, ambling chemistry, and to the degree that one grades on a curve and takes those qualities into account, they’ll find some reward herein. It also has some quite funny bits, too, both small and seeded throughout. The chief problem, though, is that the film doesn’t have a well-defined angle driving it. Lip service is paid to the idea of Shepard having a love of martial arts since childhood, but the movie doesn’t convincingly portray this, or invest the concept with enough manic, obsessed energy. Neither does Brother’s Justice tap into or define the wounded ego of a comedian seeking industry relevance via overseas box office clout — another motivating factor with which it briefly flirts.

While Shepard has a certain shaggy charm, he unfortunately plays “himself” here as a total idiot, absent any true sense or grasp of the film world business realities involved in such a wild, self-financed venture. Ergo, while often amusing from scene to scene, all of the satirical underpinnings feel flat and undercooked, unattached to a more grounded reality. Diverting, improvisational, flight-of-fancy comedy is fine, but the mockumentary format requires a stronger, more focused and honed conceit that Brother’s Justice just doesn’t possess, alas. For the full, original review, from ShockYa, click here. (Tribeca Film, unrated, 81 minutes)