Visually and technically, Half-Blood Prince is easily the best effort since Alfonso Cuaron took the series to another level with The Prisoner of Azkaban. David Yates, whose Order of the Phoenix was merely workmanlike, has made the movie his own. The prevailing mood is claustrophobia: Half-Blood Prince loves tunnels, alleys and narrow hallways; it peers through doorways, up staircases and around corners. Sometimes darkness threatens to overwhelm the frame. When the movie opens up, it's usually for something sinister: There's a breathtaking pan around a Hogwarts tower as we see Ron Weasley (Rupert Grint) snogging his new girlfriend through one window, and then Draco Malfoy (Tom Felton) plotting something awful through another.

The stuff that should be scary is scary. Harry Potter readers may recall that the novel features a number of flashbacks to Voldemort -- then Tom Riddle -- showing both incredible promise and glimmers of deep-seated evil as a young Hogwarts student. On film, these scenes are not hokey or overstated; they have real menace. There's a climactic sequence that could have deteriorated into an orgy of fancy effects, but instead it's brutal, brief, and ultimately beautiful.

Amidst the darkness, Half-Blood Prince is immensely interested in its characters as horny teenagers: Harry (Daniel Radcliffe) is after Ron's sister Ginny (Bonnie Wright), while Hermione (Emma Watson) pines for the oblivious Ron, who has his eye on someone else. Here, mileage may vary, as the movie admittedly gets a little cutesy in its (understandable) attempts to wring squeals of delight out of viewers who've watched these actors grow up as these characters. I thought it was worth it for the lovely scene of mutual commiseration as Harry and Hermione watch their respective crushes slipping away from them.

The series continues to be a showcase for great British actors, though this time mainstays like Robbie Coltrane (Hagrid) and Maggie Smith (Prof. McGonagall) have even less screen time than usual. Michael Gambon continues to do amazing work as Dumbledore, and Jim Broadbent is, of course, a welcome addition as the ingratiating Professor Slughorn. But the performance that has stayed with me, surprisingly, is that of Tom Felton as Draco Malfoy. In The Half-Blood Prince, Draco becomes the mirror image of Harry -- a teenage boy struggling under the weight of too much responsibility. Draco's storyline is severely compressed from the novel, but Felton's performance makes it breathe: With impressive economy and considerable subtlety, he takes the character from one-dimensional villain to tragic figure.

This is not a great movie. As in the past, certain storylines seem tossed in just to sate the fans -- the Quidditch seems particularly out of place here. Some characters, most notably Ron, are really just hanging around. These are problems that have plagued this franchise from the beginning, and they are to some extent unavoidable. But there is greatness here. The best Harry Potter movie not directed by Cuaron, The Half-Blood Prince is artful, elegant and consistently interesting.