“Privacy is when you lock the bathroom door while taking a pee,” explains Antonio Banderas in his reassuring chocolate-mousse baritone around halfway through Steven Soderbergh’s The Laundromat. “Secrecy is when what you are doing in the bathroom is not what people normally do.” This is a useful distinction to have spelled out during a film about the 2016 Panama Papers scandal, in which the money-laundering and tax-dodging tactics of the rich and famous were laid bare in leaked documents from the Panamanian law firm Mossack Fonseca. And Banderas and his co-star Gary Oldman – who play Mossack and Fonseca themselves – do a lot of this kind of thing in it: cordially expounding on concepts like shell companies and offshore accounts while swanning around in tuxedoes. As the German-born Mossack, Oldman deploys a ripe Bavarian accent that suggests Werner Herzog moonlighting as a sommelier. When an underling bridles at a request to fiddle the dates on his accounts, he philosophically offers: “Some peeeeple believe that time is chust an illooshun.” There’s always a justification if you look hard enough.

The Laundromat was adapted by Scott Z Burns from Jake Bernstein’s book Secrecy World, and uses the scandal as the basis for a wickedly comic full-spectrum analysis of human greed. It follows a number of characters from all walks of life who either actively plunge into or become involuntarily swept up in the tax-avoidance racket. Foremost among them is Meryl Streep’s (fictional) crusading widow Ellen Martin, who follows the thread of a low-level Texas insurance scam all the way to a Mossack Fonseca outpost on the Caribbean island of Nevis. The much-honoured actress is content to be part of the ensemble here, albeit a bigger part than you initially realise, for reasons that are too much fun to spoil in this review. But the film’s base notes of outrage and bewilderment at this hidden world of financial sharp practice are rooted in her. Its twist of moral ambiguity is, too. Ellen is ostensibly out for justice. Her husband (James Cromwell) has drowned during a ruby wedding anniversary boat trip, and since the charter company’s insurer has refused to pay out, she decides to track them down in person. But when it comes down to it, by “justice” she actually means “money”, in the form of a life-changing settlement.

See also the lightly farcical subplot in which a married Los Angeles-based businessman (Nonso Anozie) offers $20 million in Panama-based shares to his daughter Simone (an impressive turn by the young British actress Jessica Allain) to keep schtum about his affair with her roommate. The young woman is appalled, but her eyes also flash with opportunity. In short, she’s immediately compromised, even though the money itself – stashed in companies with wispy names such as Jetstream, Whitecloud and Nimbus – remains an airy figment. The sketch-show structure and do-try-to-keep-up tone both smack of Adam McKay’s 2015 financial crisis caper The Big Short, and there is no question that this is another topical comedy designed to galvanise viewers into outrage, and perhaps also action. (It ends with a thrillingly crafty monologue from Streep that drew cheers in this morning’s Venice Film Festival screening.) Even its creators aren’t spared. A section on the Delaware boom in shell companies – essentially, corporations-on-paper that are primarily used to move money around – dobs in Soderbergh and Burns themselves. “The director of this movie has five!” Oldman tuts, while Banderas marvels: “Even the writer has one.” (Soderbergh, who has directed four films and two TV series since his supposed retirement in 2013 following his Liberace biopic Behind the Candelabra, clarifies in the accompanying notes that he creates them for administrative reasons for each subsequent project, rather than using them to generate an income.)

The Laundromat often uses this kind of fourth-wall-breaking jolt to bring its point into focus, although a horribly graphic surgery montage during a China-set sequence is overkill, and makes you forget the point it’s trying to make. Still, the cumulative message comes over loud and clear, the fun and indignation make for a tasty, bracing cocktail. This is a film that wields its sledgehammer with panache.

The Laundromat will be released in select UK cinemas on Friday 27 September and on Netflix on Friday 18 October.