But no, there's nothing dirty about it, not really -- Cuarón is just having fun with the neverwhere between childhood and adolescence in a deliciously metaphoric way that Chris Columbus wouldn't or couldn't venture near in Sorcerer's Stone and Chamber of Secrets. Partly that's a function of the increasing sophistication of Rowling's story as her hero grows up; mostly it has to do with the fact that Cuarón is an infinitely more sophisticated filmmaker than Columbus. I loved Columbus's Harry Potter because it was Harry Potter, not because it was great film; I adore Cuarón's Harry Potter because it's pretty darn near a great film that just so happens to be Harry Potter, too. This is a children's movie that grownups don't have to be embarrassed to love.

Creepy and visceral, this truly is a grim fairy tale, in which Harry (Daniel Radcliffe) faces greater fears and greater dangers than ever. And I'm not talking about Sirius Black (Gary Oldman: Hannibal), the madman who's escaped from the wizard prison of Azkaban and seems to have it in for Harry, because what powerful lunatic wizard doesn't? Before Harry even arrives back at Hogwarts School of Witchcraft and Wizardry for his third year there, it's clear that the peril to Harry will come mostly from within himself. Cuarón -- and returning screenwriter Steve Kloves (Wonder Boys) -- treat hostile, moody adolescence in a downright Kings-ian manner. Stephen King, that is: Harry is full of rage and verging on relishing too much the potent occult power he commands, and the explosion of furious magic he aims at Uncle Vernon's (Richard Griffiths: Sleepy Hollow) sister, Aunt Marge (Pam Ferris: Death to Smoochy), reminded me of Carrie at the prom, finally bullied and abused beyond a breaking point. Not that Marge doesn't richly deserve her comeuppance -- which is gratifying in a blackly whimsical way that invokes Willy Wonka and the Chocolate Factory -- but it disturbed me in a way that the books didn't until the fifth installment: What happened to our little boy, our nice, sweet Harry?

If Rowling's genius is in not letting her kid characters stagnate but in choosing deliberately to explore their maturation in a way that few, if any, examples of children's literature have done before, then the films' producers' is in choosing someone like Cuarón to take the reins for Prisoner of Azkaban. Not only is Harry getting prickly, but his friends Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson) are growing out of their childhood skins in unexpected ways, and Cuarón plays everything about their lives in a minor key. The soundtrack rings with familiar themes, now presented in simple arrangements on ancient instruments rather than the lush orchestrations of the first two films. The sets are full of mysterious corners and secrets like they weren't before; the Leaky Cauldron pub now looks genuinely old and decrepit; the castle that houses Hogwarts now sits among a much rockier, rougher landscape. Colors are muted, and the use of handheld cameras lends an intimacy and sometimes a claustrophobia that's exactly right. Even the costumes reflect the squirmy at-oddness of a character's frame of mind: the tie of Harry's school uniform is always askew.

Prisoner of Azkaban may be too intense for very young children, but I don't mean to give the impression that it's unrelentingly bleak. The humor, too, is correspondingly more sophisticated, measured in the cleverness of Cuarón's little touches: the students' faces painted in their house colors as they cheer on a quidditch match, the wizard in The Leaky Cauldron reading A Brief History of Time, the magical notes passed surreptitiously in class, even the Monty Python-esque hint about the Whomping Willow shedding its leaves all at once in the autumn. But even the laugh-out-loud stuff -- like the outrageously funny sequence on the Knight Bus, the wizard take on mass transit -- sends a weird little tickle of uneasiness down your spine: these magic people are nice but odd in a fundamental way.

There's mood here, slightly uncomfortable, often utterly scary mood. This -- yes! -- is what a Harry Potter movie should look like, should be, was meant to be, a big box of dark, bitter, luscious chocolate.