THE FIRST TWO films adapted from J.K. Rowling's hugely popular series got the job done: under the steady hand of director Chris Columbus (Home Alone, Stepmom, Mrs. Doubtfire), Harry Potter's first steps into wizardry were glossy, literal, and easy to digest; they also earned about a kajillion dollars each. Kudos to Columbus and the series' other producers, then, for daring to shake things up with a new director. Alfonso Cuarón (Y tu mama también) takes a moodier, less whimsical approach perfectly suited to Prisoner of Azkaban's darker story line, which involves an escaped killer with connections to Harry's troubled past, sinister supernatural prison guards, nighttime chase scenes, creepy omens, and the like. Even the Quidditch match takes place during a downpour. Hogwarts seems more real than ever, thanks to some gorgeous cinematography that fleshes out the school's grounds and surrounding forest, where several key scenes are played. As in the previous films, the many special effects are top-notch. But the real success of all three films, and Azkaban in particular, can be chalked up to the performances. Of course, the adults are played by a who's who of British all-stars (new this go-round: Michael Gambon, subbing for the late Richard Harris as Dumbledore; Gary Oldman in a brief but memorable turn as the titular prisoner; and Emma Thompson and David Thewlis, both spot-on as additions to the Hogwarts faculty). More important, though, the younger cast – Rupert Grint as scaredy-cat Ron, Emma Watson as know-it-all Hermione, and especially Daniel Radcliffe as Harry – all nail it, proving there's room even in the biggest blockbuster for believability and heart. (Cheryl Eddy)