In 1966, the Czechoslovakian filmmaker Jiri Menzel played his part in his country’s New Wave with “Closely Watched Trains,” his Oscar-winning movie about a hopeless railroad worker during the Nazi occupation who volunteers for a suicide mission. Based on a novel by Bohumil Hrabal, it was in fact a comedy, in accordance with a national strain of black humor that would meet a failed suicide attempt with a wry smile. For his new film, “I Served the King of England,” the 70-year-old Mr. Menzel has again adapted Hrabal’s work, but this sumptuous, almost musically orchestrated comic fantasy founders without a well-defined edge or, for that matter, a compelling lead actor.

The film, which opens in the city on Friday, begins in prewar Czechoslovakia and is hitched to the fortunes of Jan Díte (Ivan Barnev), a mustached, short-stack hot dog salesman who is equal parts wily and naïve. Taking on the trade of waiter, he shinnies up the totem pole from bar-café to industrialist resort to Art Nouveau restaurant in Prague. Along the way, he tickles the fancy of a nubile brothel prostitute, tosses coins to watch people scramble, and outwits a masterful head waiter.

With the rise of the Nazis, Jan’s adventures continue as he falls for a fetching pigtailed fräulein, one of the ethnic Germans living in his country before the Sudetenland “annexation.” Liza (Julia Jentsch, of “Sophie Scholl: The Final Days”) recites Aryan propaganda, but Jan pays no mind. He even sets to work in the resort that’s now a Nazi master-race farm swarming with statuesque naked ladies. Punctuating these episodes are future scenes of an older, contemplative Jan (Oldrich Kaiser), holed up in a forest cabin after years of Communist-era imprisonment.

“I Served the King of England” breezes along on charm for quite a while, despite Mr. Barnev’s relative lack of charms. Though an able physical comedian, careening along with trays laden with cups and saucers, the actor fails to imbue Jan with much of a presence or sensibility. By the second half of the movie, the void becomes wearying, even for viewers distracted by Mr. Menzel’s almost old-fashioned Euro-cinema adherence to “the female form.” (The women, almost without exception, are presented as feasts for the eye, and once literally on a platter.)

Mr. Menzel, who tinkers with Hrabal’s book, punts on the tricky issues of identifying with Jan. He omits the source material’s more unnerving episodes and details, unspooling the film with a tin ear for tone throughout. And the older Jan’s scenes, shuffled in instead of chronologically presented, border on the incoherent. If all this is meant to be an especially subtle black comedy, somebody needs to strike a match.

One of the first lessons Jan learns as an apprentice waiter is the oxymoronic but shrewd advice to see and hear nothing — and everything. This and other moments are ripe for addressing the dicey wartime climate for a subjugated independent country, but Mr. Menzel doesn’t lay out his ideas as well as he does the candy-colored spectacle. (For damning comparisons, see the concerted use of whiplash narrative drive in Paul Verhoeven’s “Black Book” or the visceral blood-warm sensuality in Volker Schlöndorff’s “The Tin Drum.”) There’s also something squandered in Jan’s ordinary selfishness as he aspires to make big bucks just like the childlike industrialists, seemingly oblivious to national loyalty.

“I Served the King of England” must have held a special attraction for Mr. Menzel, not least because of the Communist-imposed restrictions he once shared with the late Hrabal (and in a way, Jan). Both the writer and the filmmaker created works that were put on ice by authorities; Mr. Menzel endured a long period of state employment without actual permission to make movies. But despite the odd terrific slippery twist of the knife (such as Liza’s Hitler fixation during sex with Jan), the movie is a vivid but unsatisfying revisiting of a fraught period in Czech history.