At last it can be told: despite the $900 million it made at the global box office, despite its ranking as the highest-grossing film of 2001, director Chris Columbus was not entirely happy with Harry Potter and the Sorcerer's Stone. "I always thought we could have gotten the visual effects better," he says. The pacing of the film, he admits, was a bit sluggish. "The first 40 minutes of the first Harry Potter film were introductions."

On Nov. 15, when the bespectacled wizard returns in Harry Potter and the Chamber of Secrets, based on the second novel in J.K. Rowling's blockbuster series, fans will see a bolder, more menacing, faster-paced movie — and to put it bluntly, a better one. "It's more of everything," says Daniel Radcliffe, 13, who once again plays Harry with brainy subtlety (but whose voice has dropped a good octave). "And it's a lot darker."

It is also much scarier. The movie mirrors the progress of Rowling's books, which become more sinister and intense as they go along. In the new film, a dead cat is hung in a hallway at Hogwarts School of Witchcraft and Wizardry; children are frozen stiff (or "petrified") by a monster; Harry and his sidekick Ron (Rupert Grint) are attacked with surprising violence by a monstrous Whomping Willow after crash-landing in its gnarled branches in a flying car. Later, they're chased through the Forbidden Forest by an army of giant spiders.

Warner Bros. was afraid that the movie would receive a PG-13 rating — a dangerous proposition, since Potter's most devoted fans are preteens. Just as important, the core consumers for Potter toys, which generated about $500 million in sales last time around, range in age from 7 to 11. Instead, the film is conveniently PG, like its predecessor.

Still, the filmmakers are eager to let you know that your children may be afraid, very afraid. "I would strongly caution parents," says Columbus, "anyone who has a 7-year-old or younger, to make sure they know what they're getting into."

His warning is the cinematic equivalent of a parental advisory on music, a not entirely unintentional come-on to older teens and young adults who thought the last Potter film skewed too young. In the posters for Chamber of Secrets, Harry looks intense, and he's holding a sword. It's an image designed to appeal to older audiences, the same moviegoers who embraced the other movie franchise launched a year ago, Lord of the Rings.

The competition between Lord of the Rings and Harry Potter — the sibling rivals of the AOL Time Warner entertainment family — is intense. Last year's Fellowship of the Ring, the first of three J.R.R. Tolkien — based movies to be released by the company's New Line division, came in second at the box office behind Harry Potter. Unlike Potter, however, it ended up on numerous critics' best-of-the-year lists and received 13 Oscar nominations, including Best Picture. (The Sorcerer's Stone received only three.)

This time it's widely assumed in Hollywood that Lord of the Rings: The Two Towers, set for release on Dec. 18, will outgross Chamber of Secrets. Potter mania seems to have quieted a bit, in part because Rowling hasn't published a novel in two years. (The author says she will deliver the fifth of an eventual seven Potter books in 2003.) While Sorcerer's Stone pulled in $318 million domestically, this one is expected to make closer to $250 million — still an impressive number. And it will undoubtedly win the merchandising race. Potter toys are already selling briskly, and stores have even reported shortages on Lego's Chamber of Secrets tie-ins, according to Jim Silver, publisher of Toy Wishes magazine. Lord of the Rings' merchandise has also been successful, but less so because of its older audience and later release date.

Going into his second year at Hogwarts, Harry is more heroic, and so is Columbus. While he was accused of being too slavishly faithful to Rowling's book the first time around, in Chamber of Secrets the director gives his imagination freer rein. In the new film, Quidditch — the ball game played by young witches and wizards on broomsticks — is as exciting as a car chase. Harry's showdown with a terrifying serpent surpasses even the most imaginative readers' expectations. It all adds up to a 2-hr. 42-min. movie--9 min. longer than Sorcerer's Stone. "The length didn't seem to be an issue last time," says Columbus, "but I wanted this film to feel as if it moved much quicker."

The movie still feels too long at times; that's the price you pay for seeing so much of the book on screen. But the inexperienced young stars are much livelier than before. This is especially true of Emma Watson, 12, as the know-it-all little witch Hermione Granger. While filming Sorcerer's Stone, Columbus often stepped into the scene, just off-camera, and coached the actors line by line. "I do a little of that now," says Columbus, "but they can literally get through entire sequences without me interrupting them."

Some things in Potter's world, though, haven't changed. Production designer Stuart Craig's Diagon Alley — the teetering jumble of Tudor and Georgian magic shops — is still standing. The original cast is intact, including Maggie Smith as Professor McGonagall, Robbie Coltrane as Hagrid and, as the wise Professor Dumbledore, Richard Harris. The Irish actor, who suffered from Hodgkin's disease, died at age 72 on Oct. 25. No word yet on who might replace him, but the character does appear in the third Potter flick, The Prisoner of Azkaban, which will go into production in spring of 2003.

With each movie, Rowling seems to be stepping back; Columbus says she did not visit the set of Chamber of Secrets. "I think she was busy writing the fifth novel," he says. "She's there if we need her, but she trusts us now." The author did give her blessing when it came time to find a new director for Prisoner of Azkaban. Says Columbus, who will shift to executive producer on the next movie: "I really thought halfway through the second one, 'It's been almost two years since I've had dinner with my family during the week.'"

His replacement is Alfonso Cuaron, a surprising choice, since his most recent film was Y Tu Mama Tambien, this year's racy, critically hailed Mexican road movie about two teenage boys and an older woman. But Cuaron also has experience adapting the works of esteemed British authors — Frances Hodgson Burnett (1995's A Little Princess) and Charles Dickens (1998's Great Expectations). Prisoner of Azkaban isn't scheduled until summer 2004, so there will be no new Potter film next year. This will allow Radcliffe to spend time in a normal school rather than with tutors on the set. Though the world is watching Radcliffe grow up onscreen, he insists, "not much has changed." Except that his world is becoming scarier.

• Jess Cagle