There's a darkness on the edge of Hogwarts, and its name is adolescence.
''Harry Potter and the Goblet of Fire," the latest big-screen installment of the unstoppable pop-culture juggernaut, marks a sea change. Just as J.K. Rowling's fourth novel -- a 734-page anvil that stood as the white-hot apex of the Potter fad -- poured a bucket of teen hormones into the Gryffindor stew, so the new film finds Harry (Daniel Radcliffe), Hermione (Emma Watson), and Ron (Rupert Grint) casting 14-year-old puppy eyes in various directions.
Friendships are torn asunder by jealousy and suspicion. There's a school dance to which Hermione actually wears a gown. Ron takes one look at her and mutters, ''They're scary when they're grown up, aren't they?"
More to the point, ''Goblet of Fire" is the entry in which Rowling finally took off the gloves -- a much-liked character dies, Lord Voldemort returns from exile with powers strengthened -- and the movie rigorously follows suit. Entire plotlines and characters have been sliced off to fit the confines of a two-and-a-half-hour running time (Winky the Elf, we hardly knew ye), but the sense of impending doom remains.
Is this the best of the series? It's beside the point. Long as it is -- and the movie verges on overlong -- ''Goblet of Fire" is the first that plays for keeps.
The director this time is not Chris Columbus, the proficient journeyman of the first two films, nor Alfonso Cuaron, who gave the third installment a dose of needed magic (which, ironically, pleased everyone except hard-core Potterheads), but Mike Newell, the British director of ''Four Weddings and a Funeral" and ''Donnie Brasco" (and ''Mona Lisa Smile," but we'll let that slide, although Hogwarts could possibly pass for Wellesley College on a lousy day). Newell specializes in relationships rather than special effects, and, fittingly, ''Goblet" is most interested in the curses and enchantments of adolescent behavior.
So while the movie starts off with a Quidditch World Cup bang, the sequence feels rushed and secondary, like a highlight reel of the book's opening chapters. Soon enough, Newell assembles the relevant troops: The students of two rival academies of magic convene at Hogwarts for a grand Triwizard Tournament, with one student from each school chosen by the Goblet of Fire to take part in an enchantment triathlon.
From Durmstrang comes Viktor Krum (Stanislav Ianevski), Quidditch star and glowering Slavic jock. From Madame Maxime's Beauxbatons comes Fleur Delacour (Clemence Poesy) -- think Ludwig Bemelman's Madeline all grown up and with a wicked knack for casting spells. And from Hogwarts comes Cedric Diggory (Robert Pattinson), upperclassman, dreamboat, all-around good chap.
Then the Goblet has the effrontery to belch out one more name for the contest: Harry Potter. Because everyone assumes that Harry has engineered this development, all of Hogwarts turns against him in a fickle rage. Now this is adolescence: humiliation, isolation, an inflamed sense of social persecution that may or may not be deserved. Suddenly Harry is no longer the hero of the tale but its goat. All that's missing is acne.
The tournament's three contests provide the excuse for the expected state-of-the-art CGI whizzbangery, and they are visual marvels. A Hungarian Horntail dragon perched angrily atop Hogwarts' highest spire, a seaweedy underwater world of beastly mermaids, a maze of perversely mobile hedges -- these are images with staying power, like Arthur Rackham illustrations sprung to life. They don't feel multiplex-trendy but organic to the series' darkening tone.
The main order of business in ''Goblet," though, is the sorting out of unwelcome new loves and lusts. Harry stammers whenever he sees classmate Cho Chang (underwhelming newcomer Katie Leung), while Krum sets his shako (again, not quite believably) for Hermione. Ron just sulks; the scene in which he and Harry double-team the Patil twins (Shefali Chowdhury and Afshan Azad) at the Yule Ball is a nice study in young male doltishness. Any sparks between Ron and Hermione, by the way, will apparently have to wait until the next movie.
Strip away the special effects and you could be watching an episode of ''Degrassi Junior High," and is that such a bad thing? At times the movie squirms: Harry's encounter with ghostly Moaning Myrtle (Shirley Henderson) in a fifth-floor bathtub flirts along the line between comedy of embarrassment and full-on kink. (That the 39-year-old Henderson has 23 years on Radcliffe makes the scene even more interestingly bent.) ''Goblet" knows, though, that where some teenagers flounder others find their legs, and Harry's roommate Neville Longbottom (Matthew Lewis) makes a touching entry into adulthood here.
As for the adults, Michael Gambon's Dumbledore has a greater presence in this film, but Professors McGonagall (Maggie Smith) and Snape (Alan Rickman) are forced to the back of the line. Hagrid (Robbie Coltrane) indulges in a queasy romance with Madame Maxime (Frances de la Tour), who resembles nothing so much as a transvestite on stilts.
With any new ''Potter" entry, the newcomers hog the stage, and luckily ''Goblet" has two prize hams: Brendan Gleeson as Dark Arts professor Alastor ''Mad-Eye" Moody -- mad eye swinging like a marble in a shot glass -- and Miranda Richardson as Rita Skeeter, the perky tabloid journalist of any young wizard's nightmares.
And, of course, there's Voldemort, who rises from the depths of this film's climax like the devil himself. I'm not sure whose idea it was to cast Ralph Fiennes as the devil, but it's an inspired choice: bald, elegantly muscular, eerily noseless, and very, very unpleasant, this Voldemort provides a jolt that promises to last the entire series, wherever that may lead.
Is the movie for kids? Even with a PG-13 rating, ''Goblet of Fire" is oddly less scary in some ways than last year's ''Prisoner of Azkaban" -- less predicated on computer-generated ghoulies and funhouse shocks. The dread here cuts deeper, though. When we hear the wail of a grieving father toward the end of the movie, it's the first genuinely human moment in a ''Harry Potter" film, and it is awful.
''Soon we must all face the choice between what is right and what is easy," Dumbledore tells his rattled charges, and with those words the franchise becomes no longer a corporate toy but a metaphor for growing up in a world where magic spells are never quite enough. ''Everything's going to change now, isn't it?" asks Hermione. Yes, dear, it is.
Ty Burr can be reached at email@example.com.