The theft of artworks by the Nazis—especially from Jewish families—and the post-war effort to restore them to their rightful owners have been treated in expert documentaries like “The Rape of Europa,” and one part of the story—the attempt of the American army to rescue some purloined items while the war was still ongoing—has been the subject of a mediocre dramatization, George Clooney’s “The Monuments Men.” Now Simon Curtis (“My Week With Marilyn”) offers a well-mounted but pedestrian account of Austrian refugee Maria Altmann’s campaign to reclaim from the Austrian government several paintings by Gustav Klimt stolen from her family, The most notable was the titular one, portraying her beloved aunt Adele Bloch-Bauer in sumptuous dress, which became a national treasure sometimes referred to as the Austrian Mona Lisa.

Helen Mirren gives a canny, crowd-pleasing performance as the Altmann of 1998-2006, when the legal case was fought and Ryan Reynolds plays, earnestly but unconvincingly, her lawyer Randol Schoenberg (grandson of the composer Arnold). But much the film is devoted to extended flashbacks showing Maria’s early life in Vienna and flight from Austria with her husband Fritz in the aftermath of the Anschluss. In these Tatiana Maslany is Maria, Allan Corduner her father Gustav, Max Irons Fritz, Antje Traue Adele, and Henry Goodman Adele’s husband Ferdinand.

Without going overmuch into the extent to which the script by Alexi Kaye Campbell departs from the historical record, its portrayal of events is definitely not overly concerned with subtlety. The idyllic pre-1938 life that Maria and her upper-class family enjoy in Austria is presented as a sort of gauzy golden age, and the German storm troopers who descend on the city (as well as the Austrians who welcome them) are depicted as stock villains.

Fair enough, perhaps (at least as far as the Nazis are concerned), but when Maria and Randy (as she calls him) visit Vienna to stake a claim to the paintings, they’re greeted by government and museum bureaucrats (as well as members of the general public) who are portrayed in similarly broad strokes; it’s as though even in the aftermath of the Waldheim affair, there had been no introspection among them. Only one Austrian is singled out for admiring treatment: investigative journalist Hubertus Czernin (Daniel Bruhl), who helps Maria and Randol in their search for the truth. (One might point out that Campbell fudges the facts about the discovery of the documents regarding the ownership and bequest of the Klimts to the Belvedere Gallery, giving the credit to Maria and Randol’s surreptitious scouring of the archive while it appears that Czernin was more directly responsible for finding them. Czernin, of course, had played a role in revealing Kurt Waldheim’s unsavory past, too.)

Even more debilitating is the attempt by Campbell and Curtis to portray the relationship that blossoms between Altmann and Schoenberg in the comedy-drama vein of “Philomena.” Mirren carries off her part of the equation with customary elan, fashioning a portrait of a severe, demanding woman in whom one can still sense the pain of loss and a capacity for genuine warmth. She expertly tosses off what are meant to pass for witticisms in Campbell’s uninspired script, making them seem almost worth hearing.

But Reynolds seems at sea. The only aspect of the character he manages to capture is Schoenberg’s rather vacuous boyishness. Otherwise, though, he’s not helped by Campbell’s script, which doesn’t give him a center: at one point he’s admitting he got into the case simply because he found out how much the paintings are worth, but after a visit to Vienna’s Holocaust memorial he nearly breaks down in grief. (If we’re meant to take this as a road-to-Damascus moment, Reynolds can’t carry it off.) Nor does it help that so much time is spent on his situation at home with pregnant wife Pam (Katie Holmes, wasted). Whether it’s true or not that her water broke on the very morning he was scheduled to appear before the Supreme Court, it’s the sort of cute coincidence that in this context feels false, like so much else in the Mirren-Reynolds routine, which never achieves the rightness the one between Judi Dench and Steve Coogan did.

The lack of authenticity is exacerbated when people like Elizabeth McGovern (as a federal judge) and Jonathan Pryce (as William Rehnquist) show up in what amount to cameos, or Ben Miles pops in to do a pretty gruesome bit as Ronald Lauder, who eventually buys the gold-leafed painting of Adele. Moritz Bleibtreu’s brief introductory appearance as Klimt is nearly as frightful, and Traue fails to achieve the desired dreamlike effect as Adele. On the other hand Maslany, Irons, Corduner and Goodman manage to make many of the flashback sequences touching, despite the clichés Campbell often inserts into the dialogue, and Bruhl is as reliable as ever.

Visually “Woman in Gold” looks elegant, with production designer Jim Clay, the art direction team headed by Andrew Ackland-Snow, set decorator Jennifer Gentile and costume designer Beatrix Pasztor all contributing fine work and cinematographer Ross Emery taking advantage of it—and the beautiful locations in his widescreen images. The behind-the-camera contributions—along with Mirren’s presence—mark this as a prestige production, but the unsubtle, prosaic treatment—along with the bland Reynolds—vitiates the effort.