Dito Montel’s “Riff Raff” is a ragbag of a movie that never takes itself too seriously. There’s A-list talent on hand and an overriding conviviality of tone, along with suspense that is genuine and laughs that are earned. Mr. Montel’s shaggy dog story has parameters that are familiar but, hey, there are worse ways to spend 90 minutes.

One better way to spend that time could be to seek out a few of this film’s inspirations, especially David Cronenberg’s “A History of Violence” (2005). The casting of Ed Harris, who was also in the Cronenberg picture, can’t be coincidental, and “Riff Raff” has a rakish air to it, a light-limbed insouciance. It’s not that Mr. Montel, who worked from a script by playwright John Pollono, has made a parody of a gangster film, but the conventions of the genre are given a spin that is more tongue-in-cheek than not.

This is what one might expect of a film that counts among its talents Bill Murray, Jennifer Coolidge, and Pete Davidson. Given the blase attitude toward violence held by Messrs. Montel and Pollono, the film errs on the side of black comedy. When Hannigan (Mr. Murray) blithely blows off the head of a fruit-and-vegetable vendor, he and his colleague Lonnie (Mr. Davidson) engage in an off-hand dialogue about the politesse of homicide. The results are discomfiting — all that gore, you know — but also dry and amusing.

Mr. Murray makes the most of his role as a mobster, as does Mr. Davidson as Hannigan’s smartly dressed but not-so-smart aide de camp. These characters are, if not peripheral to the shenanigans at hand, then supporting players in an oh-so-ironic take on that inescapable and universal subject, the dysfunctional family. A winsome voiceover tells us that “family can be complicated.” Barely a minute into the film, we know we’re in for a sardonic turn of events.

When we meet our narrator, Dartmouth-bound DJ (Miles J. Harvey), he’s holding a gun to the head of a craggy old man who’s already undergone some violence. Vincent (Mr. Harris) is DJ’s step-father and his second wife, Sandy (Gabrielle Union), is DJ’s mother. That the marriage is interracial is less notable than the discrepancy between their ages. Mr. Harris looks his 74 years; Ms. Union is 52, but skews younger. Vincent is a lucky man, one thinks, but so is Sandy: She has a partner who is loving and has taken the brainy-but-clueless DJ under his wing.

Enter Vincent’s son from his previous marriage, Rocco (Lewis Pullman). He’s traveled to his father’s cozy mountain vacation retreat with a very pregnant girlfriend, Marina (Emanuela Postacchini), and his very sozzled mother, Ruth (Ms. Coolidge). This unexpected family reunion is welcomed by exactly no one except for DJ, who takes it all in with guileless bemusement. He’s entranced by the forthright Rocco, enamored of the exotic Marina, and cautious around Ruth, a woman who says what’s on her mind — that is, when she’s not guzzling whiskey.

Rocco is on the run from Hannigan and Lonnie, and is desperate for help from his estranged father. Rocco’s life is on the line, as are those of  Marina and their unborn son. Frankly, everyone’s life is on the line — Hannigan and Lonnie are ruthless. When they catch up with all and sundry, a run of family secrets are brought to light. Tempers flare, bullets fly, hearts are broken.

The majority of the story takes place in a single location, a setting that Mr. Montel proves adept at navigating. Mr. Pollano’s script doesn’t give Ms. Coolidge or Ms. Union a lot to work with — they cruise, respectively, on their timing and beauty — but all the actors are invested, and the relationship between Messrs. Murray and Davidson is deftly calibrated. 

“Riff Raff” is comfortable in its own skin and graced with a cast having a fine time of it. There’s a reason they picked up Mr. Montel’s phone call, and it’s there to enjoy for those in the mood for something proud and imperfect.