Dardenne brothers Jean-Pierre and Luc continue their extraordinary series of films about the marginalized in today’s global society—a group overlooked more often than ever by filmmakers—with “Two Days, One Night,” a remarkably concise yet powerful story of one woman’s struggle to keep a job in the face of administrative cutbacks and workplace competition.

Marion Cotillard effaces any trace of her celebrity to star as Sandra, a woman just returning to her place on the floor of a small solar panel factory after a medical leave. She’s woken by a phone call from her friend Juliette (Catherine Salee) with bad news: the shift foreman presented her sixteen co-workers with a choice, either to forgo their 1000 euro bonuses or to keep Sandra on the payroll. They’d voted 14-2, to get the bonus and let Sandra go. But if Sandra would come to the factory before it closes, perhaps they could convince the owner M. Dumont (Batiste Sornin) to hold another, secret ballot after the weekend break.

Sandra is devastated—she, her husband Manu (Fabrizio Rongione), a restaurant worker, and their two children have only just recently gotten off the dole and into a house of their own, and they’d be thrown back onto the welfare rolls if she loses her job. So though in her despair she wants nothing more than to take some pills and sleep, she allows Manu and Juliette to persuade her not only to ask Dumont to have a second vote, but to approach the other workers personally over the weekend and encourage them to vote to keep her on, even though it would mean doing without the extra pay.

The rest of “Two Days, One Night” simply follows Sandra as she and Manu travel from place to place in town, where she speaks to most of her co-workers, sometimes encountering apologies and promises of support, sometimes a regretful inability to do so, and on occasion blatant hostility. Each episode introduces a glimpse of another working-class story—the wife with a controlling husband, a father and son who so disagree over what to do that they actually come to blows, the young man concerned that voting with Sandra will endanger his own job, the woman just starting life with her boyfriend and wanting to furnish their place, the man who tearfully promises to change his vote because of how Sandra has helped him in the past, the man who needs the bonus for his daughter’s school tuition, the woman who has her daughter lie about her whereabouts to avoid seeing Sandra at all. The sequences allows the Dardennes to build up a mosaic of the realities of life among the working poor who are just getting by, perpetually on the edge of disaster.

While sketching the other workers in quick, incisive strokes, however, the focus of the film remains on Sandra as she vacillates between moments of near despair, threatening to give up the quest and perhaps even swallow all those pills she’s been prescribed, others of embarrassment as she sprints from person to person in what she sees as begging mode, and still others of euphoria mixed with weeping when a co-worker unexpectedly throws her support. No plaster saint, she’s a woman with failings; at some points you might actually think that Dumont and Jean-Marc (Olivier Gourmet), the foreman, are correct in thinking that she’s no longer up to the physical demands of the job. One might imagine Cotillard would be entirely too glamorous to be convincing in the role, but she immerses herself in it so completely that she fits in perfectly with Rongione, who’s worked with the Dardennes before, and the other members of the cast, some of them nonprofessionals.

The authentic character of the ensemble is matched by the typically naturalistic look of the film, with Alain Marcoen’s spare cinematography, which favors close-up, extended tracking shots of Sandra as she pushes forward or crumbles back into despair, capturing the shabby atmosphere of the small Belgian industrial town where the action is set—a mood enhanced by Igor Gabriel’s unassuming production design. As is usual in much of their work, the Dardennes eschew background music, with only a couple of pop tunes heard coming over the radio to comment on events as they occur.

“Two Days, One Night” isn’t essentially a suspense movie, of course, but its structure certainly forces you to wonder whether Sandra will succeed in changing seven of the original votes to secure the majority that will save her job—in the same way that one is meant to wonder whether Henry Fonda’s Davis will persuade the other jurors to vote for acquittal in “Twelve Angry Men.” And inevitably you find yourself cheering her on. One might foresee a simply triumphal denouement, a celebration of worker solidarity. But the Dardennes are shrewder observers of society than that: they contrive an ending that presents a credible view of both workers and management, yet allows a sense of idealism to survive even in a world dominated by concern with balance-sheets.

A little too clever, perhaps, but still a highly satisfying conclusion to yet another fine exercise in the Dardennes’ impassioned neo-Neorealism.

Even a filmmaker with the deftness of Wes Anderson would have had trouble breathing some whimsical life into this arch, flagrantly artificial comedy, and David Koepp is no Wes Anderson. While Koepp has made a couple of really good suspense-horror movies, “Stir of Echoes” and “Secret Window,” and his previous comedy (“Ghost Town” with Ricky Gervais) was a sweet, amiable trifle, “Mortdecai” is a thoroughgoing disaster, a misfire so complete that one can only wonder why anyone ever thought it was a good idea to expend so much effort, money and production flamboyance on such drivel, which aims to be a larkish homage to caper movies of the sixties but falls dismally short of the target.

Johnny Depp, who seems to be doing a riff on the young Laurence Olivier, plays the title character, a pseudo-aristocratic British twit married to the luscious Johanna (Gwyneth Paltrow). Charlie’s a con-man in the art world, but his luck has run out and he’s facing a huge tax bill. He’s also being given the cold shoulder by his wife, who finds the extravagant moustache he’s growing—a thing that, along with the gap between his front teeth, also makes him look like Terry-Thomas—not just laughable but gag-inducing when they try to kiss. (He responds sympathetically by gagging too.)

Enter Inspector Martland of MI5 (Ewan McGregor), an old school rival for Johanna’s affections still besotted with her, who uses Mortdecai as a conduit to the underground art market and enlists him in investigating the murder of an Oxford painting restorer and the theft of a lost Goya she was working on. Her murder is quickly identified as the work of terrorist Emil Strago (Jonny Pasvolsky), but his motivation for stealing the painting is unclear, and in any event it was stolen from him shortly after the theft.

It would be as tedious to relate in any detail the convolutions of the complicated plot as it is to sit through this witless exercise in japery. Suffice it to say that it takes Mortdecai—always accompanied by his insanely loyal, incessantly girl-shagging manservant Jock Strapp (Paul Bettany)—from London, where he consults with snooty Goya specialist (Michael Culkin) and consults with mechanic-smuggler Spinoza (Paul Whitehouse) over the sale of a Rolls Royce, to Moscow (where he’s taken after being kidnapped by a brutal art collector named Romanov, played by Ulrich Thomsen) to Los Angeles, where he accompanies the Rolls to its buyer, art collector Krampf (Jeff Goldblum) and his nymphomaniac daughter Georgina (Olivia Munn). Along the way there is a constant stream of unfunny slapstick fights and adequately staged but equally unfunny chases, with Mortdecai blabbering out what passes for hip commentary at each stage of the trip. Meanwhile Johanna is being romanced in his absence by the ineffectual Martland, while doing some sleuthing of her own—which culminates in a revelation about the much-sought painting involving a befuddled old duke (Michael Byrne) and Hermann Goering.

Depp certainly throws himself into the title role, apparently thinking that Charlie Mortdecai is the next Jack Sparrow. He’s not, and it’s exhausting and depressing watching the actor trying to endow the tiresome character with a degree of interest as he scrambles through scene after scene, reciting his lines in an accent that might best be relegated to a Monty Python Ministry of Silly Talks. Paltrow tries to do a sort of Grace Kelly routine with minimal success, while the usually affable McGregor comes across as a dull stick indeed. But it’s certainly Bettany who gets the short straw, trapped in an embarrassing role that requires him to do an imitation of Jason Statham. The other cast members, except for the dull Pasvolsky, are fortunate in that their parts are very small. But that’s understandable since Depp, who also produced, sucks up most of the air, and running-time, with the brand of ostentatious shtick that has unfortunately become his default setting. Sad to say, this talented actor is threatening to turn into a modern-day Jerry Lewis.

The only saving grace of “Mortdecai” is in the visuals. Production designer James Merifield, art director Patrick Rolfe, set decorator Sara Wan and costume designer Ruth Myers outdo themselves in providing settings that resemble the frosting on a cake, and cinematographer Florian Hoffmeister captures their work—even when it’s deliberately crass—in lush, shiny tones. The transitional sequences that use visual effects to show the changes from one locale to another give the movie some momentary energy, which it desperately needs, since Koepp’s staging of the live action is for the most part flat and enervating despite Depp’s constant showiness, a failing that’s exacerbated by the desultory editing of Jill Savitt and Derek Ambrosi. Mark Ronson and Geoff Zanelli’s attempt to pump things up musically doesn’t work either.

Koepp’s picture won’t be around long. But Johanna’s gagging over Mortdecai’s moustache could set a trend. Viewers certainly have good reason to do the same while watching the movie.