When the mighty fall, they fall hard.
Writer-directors Joel and Ethan Coen, who each have four Academy Awards on the mantelpiece and were nominees again this year for their script for Bridge Of Spies, descend from the filmmaking firmament with a sickening thud.
Hail, Caesar!, the brothers' screwball valentine to the golden age of 1950s Hollywood when studios nurtured, protected and controlled big name stars, is a deeply disappointing exercise in period style over substance, characterisation and wit.
It's hard to believe that the mercurial siblings who gave us The Big Lebowski, Fargo, O Brother, Where Art Thou? and No Country For Old Men could be responsible for this flimsy whimsy.
Admittedly, there are a couple of stand-out musical sequences that quicken the pulse and remind us of the Coens' genius.
These crescendos are spliced and shoehorned into the film's trailer, which runs to a trim two and a half minutes, and is infinitely more enjoyable that the bloated 106-minute misfire that has been haphazardly bolted together in the editing room.
As usual, the ensemble cast shimmers with comic talent, but here, almost everyone is squandered in thinly sketched roles.
Eddie Mannix (Josh Brolin) masterminds production at Capitol Pictures, keeping the tawdry secrets of his leading men and ladies out of rival gossip columns penned by twins Thora and Thessaly Thacker (Tilda Swinton).
He also has to massage egos on and off the set of the studio's big budget epic, Hail, Caesar! - A Tale Of The Christ, starring matinee idol Baird Whitlock (George Clooney).
When a Communist group calling itself The Future kidnaps Baird, Eddie races against time to pay the 100,000 US dollar ransom and keep the abduction secret from the filmmaking community.
Meanwhile, Eddie must conceal the pregnancy of synchronised swimming actress DeeAnna Moran (Scarlett Johansson) and convince revered director Laurence Laurentz (Ralph Fiennes) to cast singing Western dreamboat Hobie Doyle (Alden Ehrenreich) in his romantic period drama.
"My readers don't care about Hobie Doyle - he wears chaps!" remarks Thora Thacker coldly.
As the situation with Baird spirals out of control, Eddie calls upon the services of chain-smoking film editor CC Calhoun (Frances McDormand), agent Joseph Silverman (Jonah Hill) and tap-dancing leading man Burt Gurney (Channing Tatum).
Hail, Caesar! is depressingly light on laughs and the Coens' trademark eccentricities.
The fleeting appearance of a sparkling one-liner - "God doesn't have children, He's a bachelor and He's very angry" - breaks up the mediocrity.
Some vignettes are stretched to the point of discomfort, such as Hobie's attempts to master one line of period dialogue ("Would that it were so simple").
Even the woefully underused Tatum is reduced to dancing for his proverbial supper in a tight-fitting sailor's outfit.
Magic Mike XXL, all is forgiven.