“True Story” stars Jonah Hill, an actor famous for such comedies as “Get Him to the Greek,” “Superbad” and the “Jump Street” movies. But this film is no laughing matter. And exactly what it’s trying to say is lost in trails of deceit and misdirected ambition.

In the deadly serious “True Story,” Hill co-stars with James Franco, his fellow cast member in the 2013 comedy, “This is the End.” Based on the nonfiction book by former New York Times reporter Michael Finkel, “True Story” chronicles Finkel’s fall from globetrotting journalism star to memoir writer and true-crime reporter.

Hill employs the dramatic chops he used so effectively in “The Wolf of Wall Street” and “Moneyball.” In his opening “True Story” scene, he plays the determined reporter on the international beat. On assignment in Africa for a story about modern-day slavery, he persuades a reluctant interviewee to talk.

“I want to help you,” Finkel insists. “But I can’t help you if you won’t help me.”

Finkel gets what he’s looking for. But then his enrichment of the facts, you might say, leads to a humiliating, debilitating downfall. After he adjusts significant details for the sake of drama, Finkel’s fabricated story runs on the cover of The New York Times Magazine.

Finkel’s editors later ask him point blank about the discrepancies between facts and his story. “You lied,” one of the accusing editors says. He’s caught; he’s fired.

Before the dismissal, the movie shows in a few short scenes how much Finkel has to lose.

Hill’s Finkel breezes into The Times’ newsroom, riding the high he’s feeling from the latest of the many magazine covers he’s written. He’s a star, and his less lustrous colleagues can’t help but know it.

When Finkel’s days at The Times are suddenly over, the ex-reporter retreats to a rural cabin near snowy Bozeman, Montana. He tells his girlfriend, Jill, “I can be working again by summer.” It won’t be that easy.

Until the lives of Finkel and Franco’s character, Christian Longo, intersect, “True Story” tells their stories in parallel lines. A dreamlike hint that Longo killed his entire family precedes a scene in which he charms a young German tourist in Mexico. He introduces himself as Mike Finkel. The ruse sets an encounter between Longo and the real Finkel in motion.

In a relationship forged in letters and a prison visiting room, Hill’s disgraced journalist is hot, and Franco’s alleged killer is cool. Finkel, grabbing for anything, agrees to write Longo’s story. It could be the story of a lifetime and the ticket back to professional journalism.

“I want to tell you my side of this,” Longo promises.

But alongside Hill’s intense Finkel, Franco’s Longo is too low-key and slippery to make much impact. Longo can be expected to be evasive, but he’s just too frustratingly elusive.

Meanwhile, Hill is completely credible as Finkel. It’s as if Hill is in one movie, Franco in another. Why their characters collaborate, what they’re actually doing within this opaque story, is the movie’s real mystery.