Overworked Eddie Mannix (Josh Brolin) is a "fixer" -- he's employed by the Capitol Pictures movie studio during Hollywood's 1950s golden age in order to clean up the messes made by actors who can't stick to the morals clause in their contracts, and to distract snoops like competing gossip-columnist twins Thora and Thessaly Thacker (Tilda Swinton in a dual role that's equal parts Hedda Hopper and Connie Marble from Pink Flamingos) from spilling the beans about who's queer, who's knocked up, and who's a scandal waiting to happen. Mannix is deeply Catholic, but his guilt is oversized compared to his sins (he visits confession daily to report on each cigarette he shouldn't have smoked, exasperating even his priest). So when the studio's biggest star, Baird Whitlock (George Clooney), goes AWOL from the sword-and-sandal epic he's shooting, it's up to Mannix to smooth over his disappearance and determine where he's gone on a bender this time. Little does he know that Whitlock is munching finger sandwiches at a teatime "study group" held at a seaside estate, where many, shall we say, progressive screenwriters are in attendance and the host's dog is named "Engels." The Coen brothers indulge their desire to be the head of their own movie studio in Hail, Caesar!, larding Mannix's story with authentically vintage scenes from Capitol's upcoming release slate: a singing-cowboy oater, a debonair parlor drama, a biblical epic, a musical, and an Esther Williams-style aquatic ballet. So what if swimming sensation DeeAnna Moran (Scarlett Johansson) stomps off the set in her mermaid costume, demanding that someone get her out of her "fish ass" so she can have a cigarette? In the moments when she's floating around at the center of a kaleidoscope of chorines, her winning smile has a wattage long lost from American movies. (And speaking of star power: It is such a pleasure to watch Channing Tatum's incisive, vigorous physicality onscreen, whether it's as an Olympic wrestler in Foxcatcher or an adult entertainer in Magic Mike, or here as a song-and-dance man performing an extended Anchors Aweigh-style musical number in sailor whites. He belongs to that rarest class of actors whose physical intelligence is the wellspring of their charisma -- indeed, the last great one before him was Bruce Lee, and before that, Gene Kelly. Jackie Chan was an exceptional athlete and John Travolta a great dancer in their respective primes, but they lacked the vital quality shared by Kelly and Lee and Tatum: You can see their muscles thinking.) The citizens of a Coen brothers' movie generally do not have character arcs. They are born whole in their first frames embodying certain attributes, like virtuous Marge Gunderson or murderous Anton Chigurh or thoroughly mellow Jeffrey "The Dude" Lebowski, and while they might suffer as a result of their unchangeable natures, they do not seize on painful experiences as an opportunity for growth. Sometimes this can be an exhilarating way for morality tales to unfold in ordinary spaces, as in Fargo or No Country for Old Men; and sometimes it can just be a mess, as when J.K. Simmons' CIA honcho in Burn After Reading echoes the audience's thoughts by declaring, after a particularly convoluted debriefing, "Report back to me when this all makes sense." Hail, Caesar! falls somewhere between the two. It wants to be a chronicle of Mannix's moral crisis as a good man in servitude to a decadent system, with multiple shots of clock faces standing in contrast to Hollywood's unchanging, carefree (and conscience-free) "now." But Mannix's ethical epiphany tiptoes in and out of the room so quietly at the climax that it's easy to miss, and its meekness opens an opportunity for the audience to shrug and say "So what?" to all of the admittedly entertaining high jinks that came before. The most important shot in the movie slides by without comment. There's a scene in the aquatic musical in which Moran rises crowned and beaming out of the water like Venus on the half-shell, skin and hair and swimsuit perfectly dry -- a little bit of vintage Hollywood illusion usually created by lowering the actor into the water and then running the film in reverse. But a moment later, she wrenches off her crown and stomps off the set, planting her butt in a chair and lighting a cigarette, all while still bone-dry. Is this a world where actors can emerge from the water without a drop on them if they simply will it? Or if their star power permits it? What's even stranger, none of the technicians on set comment on this ability -- it is quickly accepted and forgotten, as if it's a truth of this world in which the normal rules of behavior, whether related to sin and rectitude or cause and effect, don't apply. Hail, Caesar! can't decide if it's a historically inspired drama or an allegorical work of fantasy, and yet this is not a flaw. It's a strange puzzle box of a movie, as impenetrable in its own way as Mulholland Drive, and its slippery, shape-shifting nature defies all of the usual critical assessments, except one: It's worth seeing.