In Iranian filmmaker Asghar Farhadi’s films, reasonably straightforward set-ups — a divorce, a missing woman, a newly lent apartment — unspool such complex, cascading developments that it comes as no surprise that a found handbag stuffed with gold coins leads to countless fl uctuations of fortune and anguish in his latest, “A Hero.” In movies, we tend to reserve the term “magician” for more spectacle-driven filmmakers who spin visual- effects illusions. But Farhadi’s mastery is at least equally spellbinding, even while being rooted in realistic domestic dramas, with Tehran traffic usually buzzing all around. His films (including the Oscarwinners “A Separation” and “A Salesman,” the early masterwork “About Elly” and the French drama “The Past”) are schematically drawn, full of twists and turns so seamless as to be invisible.

Elaborate mechanics are deftly hidden in engrossing, minutely observed stories. Before you know it, a melodrama of modern life has been woven so tightly with psychological suspense that you can hardly breathe. “A Hero,” in which Farhadi returns to his native Iran after a trip to Spain for 2018’s “Everybody Knows,” is one of the most labyrinthine moral tales you’re likely to encounter. Rahim (Amir Jadidi) is imprisoned for a debt he couldn’t pay. We first meet him while he eagerly takes a two-day leave, meeting with his girlfriend Farkhondeh (Sahar Goldust), who clutches her lucky discovery, one that may free her love and allow them to marry.

The discovered gold, though, doesn’t add up to quite enough to satisfy his creditor, a miserly printshop owner named Hossein (Ali Reza Jahandideh). Rahim makes the decision to instead report the lost bag and return it to its owner. How much this decision is altruistic or a bit of self-preservationist cunning is open to interpretation. As played by Jadidi, Rahim has an ingratiating, hangdog demeaner; he’s almost always smiling, unless worry has clouded his expression. We are, undoubtedly, rooting for him. Rahim’s good deed earns him widespread congratulations for his selfl essness. Prison officials rush to invite television cameras to broadcast Rahim’s story, which then spreads like wildfire on social media. Donations pour in that could release Rahim from his debt.

Happy ending, right? No, “A Hero” is just getting started. Farhadi’s film, which he also wrote, grows increasingly knotty with fictions to cover truths, and vice-versa. Hossein refuses to accept Rahim’s transformation into celebrated saint. Questions of seemingly minor significance — why Rahim put his prison’s phone number on the poster advertising the lost bag, for instance — take on vital importance. As “A Hero” spirals through the tangled connections of family and business in Iran (Hossein is Ramin’s exwife’s brother-in-law; Ramin’s main support is his sister’s husband, played by Mohsen Tanabandeh), the messy injustices of public life have swelled like the traffic that envelopes the movie’s staggering fi- nale, maybe the most vivid and powerful of Farhadi’s endings. “A Hero,” an Amazon Studios release, is rated PG- 13 by the Motion Picture Association of America for “some thematic elements and language.” Running time: 127 minutes. In Persian with English subtitles. Three and a half stars out of four. By Jake Coyle