In Harry Potter and the Half-Blood Prince, the gang at Hogwarts School of Witchcraft and Wizardry enters the molten thick of adolescence - and the director, David Yates, and the screenwriter, Steve Kloves, reward them with a film that bubbles and pops with humor and feeling.
The movie leaves you sated, yet wanting more - just what you want from a series with two entries left to go. It would be a first-rate fantasy even if the audience weren't invested in the fortunes of boy wizard and "Chosen One" Harry Potter (Daniel Radcliffe) and his best friends, Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson).
But viewers will respond with paroxysms of affection for actors who rediscover and freshen their characters as they grow from children to complicated young people.
When Harry maneuvers to get two teachers drunk for one of them to spill out a dark secret, Radcliffe unites merriment and urgency in odd, purposeful grins. Watson isn't just a touching, brainy charmer; she's also a game, resilient performer, with quicksilver timing.
As Hermione, she pulls off rapid turns of phrase and expression that prove alternately poignant and hilarious, whether she's reacting to Ron's public displays of affection for another girl or to Harry's potions-class success, dependent on the mysterious annotations written in his coursebook by a genius called the Half-Blood Prince.
Best of all, Grint brings off sequences of unlikely athletic success and amorous silliness that are as delightful and pure as any silent clown's. The plot hinges on former Hogwarts potions professor Horace Slughorn (Jim Broadbent), a would-be posh wizard who makes a spectacular comic entrance from the coziest corner of a living room. Harry learns that Dumbledore needs Slughorn to reveal what the satanic Voldemort told him when the Dark Lord was his potions student.
Braodbent creates a playful 3-D portrait: From one angle, he's an incorrigible name-dropper; from another, he's a decent, ruefully self-aware failure. Dramatically and comedically, he's the exhilarating equivalent of the Weasley twins' Diagon Alley joke and novelty shop, always popping with surprises.
The filmmakers themselves create an endless sea of marvels. Everyone who swims through it - and especially Harry, Ron and Hermione - must master different strokes. It's no accident, of course, that Voldemort's original name was Tom Riddle. Harry and his friends must struggle to find the riddle to his and their own characters. After The Half-Blood Prince, you can't wait for them to crack it.