Despite its title, Denys Arcand’s new film is not a sequel to his “The Decline of the American Empire” (1986)—that would be “The Barbarian Invasions,” which won the Oscar for best foreign-language film in 2004. Yet while quite different from those films in narrative respects, “The Fall of the American Empire” shares with them a concern with serious socio-economic issues, which, however, it treats with a light comic touch. Arcand addresses matters like the the brutality of unfettered capitalism and the contempt for the least fortunate —the homeless—it fosters, but does so in the form of a caper movie deliberately replete with clichés of the genre.

The center of the narrative is a sack-sack deliveryman, Pierre-Paul Daoust (Alexandre Landry), who, in an opening scene with his girlfriend Linda (Florence Longpré), pontificates about the shortcomings of supposedly great thinkers. He’s a philosophy Ph.D. who’s of the opinion that truly brilliant people like him cannot succeed in a corrupt society, constantly peppering his talk with quotations from Plato and other Greek authorities. It’s no wonder that Linda, who has a young son to think of, drops him like a hot potato.

But Pierre-Paul has genuine sympathy from those worse off than he is (and frankly, he doesn’t seem that badly off, having a nice apartment filled with books). He’s a regular volunteer at a soup kitchen, and always drops a few coins in the cups of street people like Jean-Claude (Vincent Leclerc), who also works at the kitchen.

The plot kicks in when Pierre-Paul drives into a parking lot to make a delivery at a video store owned by a crook named Vladimir (Eddy King), which houses a safe housing the cash hoard of a ruthless gang. The place is being robbed by a desperate young man, Jacmel (Patrick Émmanuel Abellard) and his friend Chénier (Kémy Sty-Eloy)), who used to work for Vladimir, but the intervention of Vladimir’s security chief Morosi (Patrice Gauthier) ruins the heist. In the ensuing gunfire Jimmy and Morosi are killed; Jacmel escapes, seriously wounded, leaving all the money behind.

Pierre-Paul is terrified, but has the presence of mind to scoop up the two bags of cash and hide them in his truck, fooling the two cops—Carla McDuff (Maxim Roy) and her partner Pete (Louis Morissette) into letting him drive off with it.

But what then? The one thing Pierre is certain of is a wish to arrange a visit from an “escort” he finds on the web—one whose quotation from Racine on her site he appreciates. Aspasia (Miripier Morin), one Camille Lafontaine who takes taken the pseudonym of Pericles’ famous mistress, proves to be a true beauty, both seductive and smart. But while undoubtedly a gold-digger, she will also prove to be that old standby, a hooker with a heart of gold, and will become his confederate.

So will Sylvain “The Brain” Bigras (Rémy Girard), just out of prison for his financial crimes and now enrolled in classes to increase his knowledge of the ins-and-outs of dealmaking. Pierre-Paul approaches him to become his “advisor,” and though he’s flummoxed by the guy’s naïveté (and anxious to make a good life for his daughter), he eventually agrees, taking charge of the operation to launder the money. To do that properly, the trio will enlist a fourth conspirator, powerful lawyer Wilbrod Taschereau (Pierre Curzi), a specialist in tax avoidance and other forms of financial chicanery, who just happens to have been Camille’s exclusive sugar daddy for a time, before they amicably split.

How this unlikely crew pulls off their goal—which, of course, involves a charitable element in line with Pierre-Paul’s principles—is the main thrust of the film, but it’s juxtaposed with the police investigation, which includes interrogating Jacmel, whose involvement in the robbery brings down the wrath of Vladimir, who’s in turn being threatened by the gang. Some of the scenes in this part of the story—particularly one in which Jacmel is tortured—are surprisingly tough, and some viewers might well find them jarringly out of synch will the relatively light tone of most of the picture. There is also strong variance of tone between the cheery domestic denouement featuring Pierre-Paul, Camille and Jean-Claude, and the poignant succession of shots of actual homeless people that follows it, let alone Taschereau’s fate, which allows for a measure of heavy didacticism film otherwise avoids.

Nonetheless Arcand’s film largely succeeds, due to the adroit writing and the able work of the cast. Landry is perfect as the perpetually nervous, overeducated Pierre-Paul, and he’s seconded nicely by the attractive, engaging Morin. Even better are the wryly deadpan Gírard and the deliciously officious Curzi, the standouts in the excellent supporting cast. Arcand’s pictures have always been fairly pedestrian from a technical perspective, and this one is no exception; but Van Rokyo’s cinematography is thoroughly competent, and while Arthur Tarnowski’s editing sometimes feels a bit sluggish (the film runs over two hours), it does manage to keep the strands of the narrative clear.

The key to the movie’s success is the dexterity with which Arcand has folded his socially conscious message with witty caper comedy, even if the darker elements aren’t always a perfect fit. The distinctiveness of his approach is reflected in the background score. The original music is credited to Louis Dufort and Mathieu Lussier, but most of the music consists of a repeated eighteenth-century classical excerpt. The immediate reaction might be to assume it’s by Mozart, but it’s typical of the director’s penchant for the not-so-obvious that it’s by Haydn, and then not the well-known Franz Joseph but his more obscure brother Michael. The out-of-left-field choice is appropriate to a picture that mixes seriousness with humor, and whimsical charm with acidic irony.