CANNES – Most likely in sheer desperation at having to say anything at all about Colin Farrell dud “Dead Man Down,” veteran critic David Thomson recently turned his review into a plea to Hollywood casting directors to make bolder, braver, weirder choices — to throw gender and other demographic demarcations to the wind and let familiar screen stars become other people entirely. “We need to revolutionize casting,” he wrote, “often enough to live up to our sense of ourselves: that we are not one fixed persona — we contain multitudes.”

One can only guess whether or not Thomson was aware of Ari Folman’s bold, brave and distinctly weird new film “The Congress” when he wrote that piece, but it makes him look rather canny all the same. A loopy Hollywood satire that morphs, via a dramatic medium shift, into a poetic sci-fi fever dream, its premise represents the most literal interpretation possible of Thomson’s words: an unhappy vision of what happens when actors, and eventually everyone else, are able to detach themselves entirely from their own persona, the multitudes we contain becoming parallel beings entirely. 

If this sounds like an idea roughly cribbed from Stanislaw Lem, it is: Folman’s script is a loose riff on the Polish philospher and speculative storyteller’s 1971 comic novel “The Futurological Congress,” a morbidly absurdist work set in a world where psychotropic hallucinations have supplanted reality or most of its inhabitants. It’s heady, inscrutable material on its own, and stranger still when Lem’s male protagonist Ijon Tichy is replaced by the actress Robin Wright — not a character played by Robin Wright, you understand, but Robin Wright herself, here basking in the spotlight of the oddest fictional co-opting of a real-life movie star since “Being John Malkovich.”

It’s the most elaborate screen showcase the 47-year-old actress has had in her career, though it shows good humor on her part to be the emblem of a film that spends a good deal of screen time tell us just how over Robin Wright is. The opening scene finds the actress enduring a lambasting from her longtime agent (Harvey Keitel) on the “lousy choices, lousy movies and lousy men” (heh) that have precipitated her supposed career slump; shortly afterwards, “Miramount” studio boss Jeff (Danny Huston, effectively playing Harvey Weinstein with more capacity for hair oil) bemoans the latter-day creasing of Wright’s “Princess Bride” visage.

Their proposed solution to the decline: scanning and perfecting the actress’s image, allowing her to continue as an ageless, finely pixellated movie star while the original Wright enjoys a plush, premature retirement. Disgusted by the idea, she acquiesces for the sake of her son Aaron (Kodi Smit-McPhee, presumably not interpreting Wright’s own son Hopper), a bright kid facing the irrecoverable loss of his sight and hearing.

So far, so interesting: this live-action setup is entirely Folman’s invention, and the serious-minded Israeli director of “Waltz With Bashir” is a surprisingly enthusiastic showbiz parodist, reserving his cattiest gag for Tom Cruise later in proceedings. Moreover, the silliness of the premise nonetheless feels touchily relevant: with motion-capture performance growing more sophisticated by the year, the idea of a star vehicle with no flesh-and-blood star involvement is disconcertingly plausible.

Things come a little unstuck, oddly, when Folman finally turns his attention to the source material: the narrative leaps forward 20 years, with a sleekly aged Wright coming out of hibernation to address the masses at a Miramount congress where even more extreme developments in digital body-snatching are set to be unveiled. Folman marks this transition rather clunkily by having the 2033 Maramount empire contained within a “restricted animation zone” — which allows the director to revert to the rotoscope-style aesthetic that dominated hybrid doc “Bashir.”

Conceptually, it’s a sound enough tactic, but Folman’s chosen animation style — bright, poppy cartoonism that recalls nothing so much as the 1970s work of adult animator Ralph Bakshi, as opposed to the elegant high-contrast futurism of “Bashir” — has a near-ruinous effect on the film’s already confusing fantasy world. With the design invoking no threat, and the rules of this dayglo “zone” never clearly established (some appear able to drift in and out of it with relative fluency, while others are trapped), the film’s sense of urgency and currency take a considerable hit.

A 2D Jon Hamm, looking more like a Disney prince than Donald Draper, shows up to steer Wright through this environment of imposed hallucination — much of it closely allied to celebrity worship. (A waiter turns up looking for all the world like Michael Jackson; a Grace Jones clone nurses Wright in hospital.) Hamm rather wanly romancing her in the process, but both stars wind up playing second fiddle to the florid visual kitsch of Folman’s id, as tentacled blossoms spring up in the lovers’ wake and the two wind up doing the nasty against a mood-setting backdrop of multiple blazing aircraft — all while searching for her son, who may have become somone else entirely.

It’s precisely as bonkers as it sounds, and at two hours, both wearisome and claustrophobic. (I’m somewhat surprised, though not disappointed, that Folman resisted the lure of 3D for the animated stretch that makes up the majority of the film.) But flashes of fury and beauty remain — and I’m not just talking about the electrifying orchestral score by Max Richter. There’s something exhilarating — mesmerizing, even — about “The Congress”‘s most ludicrous flourishes. Unlike “Rebel Robot Robin,” the cloned Wright blockbuster advertised at various points in the narrative, is not a film a computer could ever conceive. Robin Wright, meanwhile, is fiercely up to the task of Being Robin Wright, and thank goodness for that.