“The Goldfinch” should be called “CliffsNotes: The Movie,” because after seeing this pedantic film adaptation, I now know all 3 billion plot points of Donna Tartt’s acclaimed 2013 novel. And, like skimming a colorless cheat sheet, I still have no clue what’s so great about it.

We witness more than a decade in the life of Theodore Decker, who is dealt a blow at 13 years old when his mother is killed in a bombing at the Metropolitan Museum of Art. He survives the tragedy and pockets the titular painting, hiding the rare work his entire life.

On his own and traumatized, Theo (Oakes Fegley) is sent to live with the Barbour family on the Upper East Side. Nicole Kidman is Mrs. Cellophane as the family matriarch.

As soon as Theo finds happiness with the WASPs, his stooge of a pop (Luke Wilson) barges in and drags the boy to Las Vegas to live with him and his trashy girlfriend Xandra (Sarah Paulson). With all the guardian change-ups, Theo’s tale can at times resemble that of Little Orphan Annie, only without fun songs or memorable characters.

There is just one fantastic creation, however: Boris, played by 16-year-old Finn Wolfhard. What a talent the “Stranger Things” star is turning out to be, containing every ounce of angsty suburban edge and humor that John Cusack and Matthew Broderick had at his age.

This time he plays a goth-ish Russian teen who’s moved around the world his whole life, and becomes a fast friend and confidant to Theo in Vegas. Fegley finally comes alive in his scenes with the lanky actor, and their boyish fun feels genuine. When Wolfhard’s portion of the movie is over, effectively so is the movie.

But, ugh, there’s still an hour left to go. Theo (now Ansel Elgort) grows up to become an antiques dealer in New York, and works alongside the mentor he met as a kid (Jeffrey Wright). It’s in their shop that a dramatic revelation about the Goldfinch painting puts his entire existence at risk.

There’s a lot of art and culture blahdy-blah in this film, but the way it’s discussed is cold and lifeless, like a bad NPR audition. Remember when Glenn Close passionately rhapsodized about literature in “The Wife” with great conviction? Here you don’t believe for a second that any of these actors know squat about paintings.

Or acting for that matter. If this was a review of a Brooks Brothers ad, Elgort would get a rave. Adult Theo wears immaculately crafted suits and has way better hair than the guy who sold you your coffee table. But the usually skilled Elgort offers nothing real beneath the bespoke jackets to make us care.

“The Goldfinch” would have been better as a mini-series, in which the writers and actors could really take the time to flesh out its clown car of characters. But, in simultaneously successfully shoving in every little thing and thus ruining the book, director John Crowley and writer Peter Straughan have killed two birds with one stone.