In “The Hobbit: An Unexpected Journey,” Peter Jackson’s adaptation of J. R. R. Tolkien’s first Middle-earth fantasy novel, Bilbo Baggins (Martin Freeman) sets out with the wizard Gandalf (Ian McKellen) and a posse of dwarfs to battle a fearsome dragon. [Spoiler alert] they do not kill the dragon, although [spoiler alert] they eventually will, within the next 18 months or so, because [spoiler alert] this “Hobbit,” which is [migraine alert] 170 minutes, is the first installment in [film critic suicide-watch alert] a trilogy.

What’s that old saying so memorably garbled by a recent president? Fool me twice — won’t get fooled again! This is not to say that Mr. Jackson is a con man. On the contrary: He is a visionary, an entrepreneur, a job creator in his native New Zealand. And his “Lord of the Rings” movies, the last of which opened nine years ago, remain a mighty modern gesamtkunstwerk, a grand Wagnerian blend of pop-culture mythology and digital magic now available for easy, endless viewing in your living room.

“The Lord of the Rings” was the work of a filmmaker perfectly in tune with his source material. Its too-muchness — the encyclopedic detail, the pseudoscholarly exposition, the soaring allegory, the punishing length — was as much a product of Tolkien’s literary sensibility as of Mr. Jackson’s commitment to cinematic maximalism. These were three films to rule them all, and they conjured an imaginary world of remarkable complexity and coherence. This voyage, which takes place 60 years before Frodo’s great quest, is not nearly as captivating.