Director Paul Weitz (“Little Fockers,” “Cirque du Freak: The Vampire’s Assistant”) opens his newest film with an aged but no less ubiquitous Robert De Niro as he walks into a parking garage and gets behind the wheel of a bright yellow taxicab. An image as loaded as that one is enough to pull an audience straight out of your film, but Weitz is content to let minds wander. And why not? After all, the biggest criticisms thrown De Niro’s way are usually jabs at his more recent lackluster performances in comparison to those of his salad days.

In “Being Flynn,” De Niro plays the titular Jonathan Flynn, a narcissistic ex-con who, after Mark Twain and William Faulkner, is the self-professed third greatest writer in American history—the only problem is he’s never been published. Upon being evicted from his shabby apartment, he reconnects briefly with his estranged son, Nick (Paul Dano), only to wind up in a homeless shelter, of which Nick, a struggling writer himself, happens to be an employee.

After 17 years without contact, Nick and Jonathan are forced to confront their lack of history in addition to grappling with their own personal demons. A decidedly somber film, “Being Flynn” runs the full gamut of human destitution. Drug abuse, suicide and homelessness are just a few of the many topics explored in the film’s 102 minutes. But Weitz, in spite of what appears to be his best effort, doesn’t quite have the focus—or track record—to keep it all in check.

The film’s weighty subject matter is confronted in a hurried pace, with the narrative jumping back and forthe through time in order to get everything across. Flashbacks within flashbacks, disorienting cross cutting and an overall lack of temporal cohesion bury “Being Flynn” in a flurry of activity. There’s quite of a lot happening on the screen, but most of it fails to resonate.

This is due in part to some lackluster characterization on Weitz’s behalf. Though the film is based on a true story (taken from the real Nick Flynn’s memoir “Another Bulls–t Night in Suck City”), the people who comprise his film are mere caricatures, from Julianne Moore’s weightless turn as Nick’s depressed mother to Olivia Thirlby’s one-note role as the Manic Pixie Dream Girl love interest.

“Being Flynn” also skirts a dangerous line between cautioning homelessness and outright romanticizing it. Nick’s tritely Bukowskian musings on skid row are hollow at best, and Weitz barely saves face with a half-hearted denouement that shoots for redemption but lands at spineless.

The film is ultimately far too neat and tidy to truly achieve the sort of emotional thrust for which it’s aiming. No matter how many scenes he stages in alleyways and garbage heaps, in homeless shelters and Narcotics Anonymous meetings, Weitz can’t seem to manufacture enough grit to make any of it matter.

His remedy: place De Niro at the forefront and let him loose. The veteran actor spends much of the film spouting nonsense in ways that echo the intensity Jake LaMotta and the inanity of Travis Bickle. In other words, “Being Flynn” feels like an excuse to force the actor back into his ’70s headspace. Weitz, like so many others, yearns for the De Niro of old, but what he gets amounts is a performance delivered by an incredibly accomplished actor perfectly content to let the past be the past.