The franchise holders took a real risk by handing this third Harry Potter film to a Mexican director who's best known for the smart, sexy but low-budget road movie Y Tu Mamá También and, more telling, the Oscar-nominated A Little Princess. But the decision has paid dividends. Alfonso Cuarón brings a darker, edgier, scarier feel to this instalment, which has boy wizard Harry (Daniel Radcliffe) contending not only with Gary Oldman's escaped convict, but also with the difficulties of becoming a teenager. But there's still plenty of fun to be had, with ghosts, ghouls and gadgets galore, the most striking gizmo being a shape-shifting triple-decker bus that, were it real, would solve London's traffic congestion at a stroke. David Thewlis, Emma Thompson and Timothy Spall join the list of cameoing celebrities, while the young leads are all growing into their roles. The film has the odd dull patch, and there are scenes weighed down by too much plot, but, by and large, this adventure is on a par with its predecessors, and, in many respects, is even better. Potter fans will not be disappointed.

Year three at Hogwarts means new fun and challenges as Harry learns the delicate art of approaching a Hippogriff, transforming shape-shifting Boggarts into hilarity and even turning back time. But the term also brings danger: soul-sucking Dementors hover over the school, an ally of the accursed He-Who-Cannot-Be-Named lurks within the castle walls, and fearsome wizard Sirius Black escapes Azkaban. And Harry will confront them all.