In what could be called the turning point of “Choke,” Clark Gregg’s directorial debut, a doctor played by Kelly Macdonald reveals that Sam Rockwell’s character may share genetic material with Jesus Christ. “So you’re saying I’m the son of Jesus Christ?” he asks. “More like His half-clone,” she replies.

There are a handful of delirious revelations like this in the film—which is adapted from the Chuck Palahniuk novel of the same name—and they threaten to push “Choke” over the precipice of the adventurous and into the realm of the dubious and downright ridiculous. For most viewers, this particular moment is one too many.

As a screenwriter, Gregg doesn’t seem to have any thematic aspirations, except for what appears to be a slavish devotion to Palahniuk’s zero-sum social nihilism and the narcissistic sexual gluttony that hastens in its wake. Whether it’s Gregg’s unsuccessful adaptation of the novel or the book’s basic incompatibility with the screen, many bits of dialogue seem more unimportant than stupid—but not by much.

Rockwell plays Victor, a 30-something sex addict who divides his time between his job as an “historical interpreter” at a colonial village, serving as a sponsor at nymphomaniacs-anonymous meetings (where he leads fellow addicts astray), and being a son devoted to a mother slipping into dementia. In his spare hours, he’s also a con man scamming money from wealthy Samaritans who are fooled by his choking act.

It’s not nearly as confusing as it sounds, but it is less satisfying than it could be. Palahniuk may write shock-literature, but he also has a message about alienation and a terminal need to belong in an America that is more concerned with institutions than people. Gregg is hesitant to explore this theme, and instead harnesses only a fraction of his cast’s abundant talent in search of cheap sex-humor that distracts from—if not totally ignores—that message.

To the extent that “Choke” has one, the movie’s saving grace is its cast. Rockwell, in his second top-billed role after George Clooney’s 2002 sleeper gem “Confessions of a Dangerous Mind,” fills Victor’s slime-caked shoes with appropriately intelligent and acerbic abandon. Rockwell excels at playing the sane man on the ship of fools, and it’s a testament to his talent as an actor that Victor flirts with his own psychological undoing in the film’s climax.

Anjelica Huston gives a typically fantastic performance as Victor’s senile mother. The tumultuous relationship between the adolescent Victor and Huston is one of the few things that Gregg seems to get right. These flashbacks are the only scenes that meaningfully treat Victor’s need to fill his parental void. while Victor bounces between foster families, Houston, a criminal and pseudo-terrorist, steals him away in bouts of blind but selfish love between arrests.

Brad William Henke plays Victor’s best friend Denny, a chronic self-gratifier. Henke is a relative unknown but he offers an earnest and emotionally present performance that seems to exist almost in spite of the film’s oppressive post-ironic atmosphere. On the other hand, Macdonald—who emerges early on as Victor’s “honest” love interest—is effectively wooden and dream-girl-by-the-numbers, though not without the afforded Palanhiuk twist that may or may not redeem her inadequacies.

Fans of David Fincher’s adaptation of the author’s first novel, 1999’s “Fight Club” must take note: “Choke” lacks the cinematic intensity, bombastic performances, and thematic density of that film. With its half-baked plotlines and tepid, almost inconsequential digressions into subplots, “Choke” raises the question of whether the novel even merited movie treatment. The film’s unusual twist does little more than further muddle the message of what was already a quiet flop.

Victor’s search for familial identity and his choking scheme clearly complement his sex addiction and the Freudian construct of the return to the womb—in Victor’s words, “Perfect, beautiful nothing.” A fitting description for “Choke”—if only it had been more inquisitive or given its viewers more credit.

—Staff writer Ryan Meehan can be reached at rmeehan@fas.harvard.edu.