LOS ANGELES (AP) – Year two at Hogwarts certainly makes for better viewing than freshman year. Yet like any school calendar overstuffed with, well, school stuff, “Harry Potter and the Chamber of Secrets” starts dragging its tail around midterms.

After an hour and a half of generally brisk action, greatly improved special effects and a decent dose of dry British humor, it feels like time for director Chris Columbus to kick it into the homestretch with a taut finale.

Instead, you’re barely halfway through, and the next hour-plus of magic and mayhem might wear down all but the most indomitable “Harry Potter” fans. What happens in these stories just is not interesting enough to merit running times edging toward three hours.

(That said, stick around through the closing credits; if you’ve hung in this long, it’s worth lingering to catch an amusing gag involving new cast member Kenneth Branagh).

The keepers of the boy-wizard franchise decided long ago to be as inclusive as possible in the movies, seemingly a reasonable move to satisfy legions of young readers who want as verbatim a translation as possible from page to screen.

But a year ago, those kids groused anyway about omissions in “Harry Potter and the Sorcerer’s Stone. They’ll grouse the same about “Chamber of Secrets,” though it runs 2 hours, 41 minutes _ nine minutes longer than the first film.

So why not cut the cute but nonessential filler and bring “Chamber of Secrets” in at a brisk, breathless two hours?

Still, “Chamber of Secrets” is fairly fun despite its length. The movie nicely blends livelier humor and a darker tinge than “Sorcerer’s Stone,” and the performances of Harry (Daniel Radcliffe) and pals Ron Weasley and Hermione Granger (Rupert Grint and Emma Watson) are much more self-assured and authentic.

While Columbus’ “Sorcerer’s Stone” essentially was a cinematic transcription of the book, he manages a bit more idiosyncrasy with “Chamber of Secrets” while sticking to the letter of J.K. Rowling’s narrative.

Good casting for new characters, expanded roles for some returning ones, dazzling sets and effects, creepy creatures and amusing dialogue and sight gags all help light a spark lacking in the first film, for all its box-office success.

Harry’s second year at Hogwarts School of Witchcraft and Wizardry is a slow buildup to his rematch with the evil conjurer Voldemort, the bad guy who killed his parents and left that zigzag scar on his forehead, and whose butt Harry kicked in the first film.

The movie touches on knotty themes of discrimination in the wizard world as conservative elements spout desires to carry out a sort of sorcerer’s ethnic cleansing and rid their realm of “mudbloods” _ those born of nonmagical Muggle parents.

All key happenings have been incorporated from the book: Appearances by house elf Dobby (a cuddly addition for young children); the ride to school in a flying car that’s all but demolished by a Whomping Willow; the targeting of Harry by an enchanted game ball during the Quidditch match on flying broomsticks, an event vastly enhanced over last year’s game thanks to George Lucas’ ILM effects house; the “petrification” of students and messages of doom written in blood on the walls; the time-traveling diary that falls into Harry’s hands; the nest of giant spiders and Harry’s battle with a massive serpent.

Richard Harris’ recent death makes his stately performance as Hogwarts master Dumbledore all the more poignant. Maggie Smith as crisp but kindly Professor McGonagall, Robbie Coltrane as noble behemoth Hagrid and Alan Rickman as sullen Professor Snape remain standouts among the adult cast.

Branagh provides great comic highlights as the preening dandy Gilderoy Lockhart, Hogwarts’ new defense-against-the-dark-arts teacher. Limited to a few seconds on screen in the first film, Julie Walters is delightfully shrill this time as Mrs. Weasley (though John Cleese as the ghost Nearly Headless Nick remains a nonentity).

Jason Isaacs, the loathsome British butcher of “The Patriot,” menacingly adds to his resume of villains as Lucius Malfoy, a bigoted wizard and father of Harry’s school rival Draco (played with increasing odiousness by Tom Felton).

Shirley Henderson makes a quirky addition as Moaning Myrtle the ghost, who offers to share the toilet she haunts with Harry in case he gets killed.

Columbus plans to remain on as a producer for the franchise’s third flick, “Harry Potter and the Prisoner of Azkaban,” due out in summer 2004. New director Alfonso Cuaron, who made 1995’s “A Little Princess” and this year’s racy Spanish-language hit “Y Tu Mama Tambien,” will be kept on a short leash in terms of closely mirroring the novel, but he brings a fresh eye and playful style that bode well for Chapter 3.

“Harry Potter and the Chamber of Secrets,” a Warner Bros. release, runs 161 minutes. Two and a half stars out of four.