For fans of J.K. Rowling's outrageously popular series of books about the world's most famous wizard, Harry Potter & the Prisoner of Azkaban far outshines the previous two film adaptations on nearly every front. The new man in the director's chair, Alfonso Cuaron (Y Tu Mama Tambien, A Little Princess) has envisioned a much darker, grittier world than did Chris Columbus, who directed the first two films in the series. The new tone is perfect for the third movie, as the mood and the themes are considerably less cheerful.

However, moviegoers who are not familiar with the book may have a harder time of it. Azkaban is not only bleaker but also far more complex than its predecessors. Even at nearly two-and-a-half hours, key elements from the novel have been excised for the sake of adaptation. While the film certainly stands on its own without prior knowledge of the book, many of the subtleties of the story and characters may be lost on these viewers.

Azkaban picks up where Harry Potter & the Chamber of Secrets left off and follows a formula that by now has become familiar to readers and moviegoers alike. As the film opens, Harry is having a miserable summer in the care of his Uncle Vernon and Aunt Petunia. This time around, his guardians are well aware of the fact that their nephew is not permitted to practice magic outside of school, so they are both less fearful and more abusive of him. Push comes to shove when the truly malevolent Aunt Marge comes to visit. When she not only berates Harry but also maligns his late parents, the young wizard can't keep his cool any longer, and he quite literally blows up his aunt. Convinced he'll either be arrested or expelled, Harry goes on the lam. Luckily, he's picked up by the Knight Bus, a sort of Mr. Toad's Wild Ride for stranded wizards, which whisks him back to The Leaky Cauldron and the world of magic that he loves.

While the threats to Harry and his classmates in the first two films were largely both fantastical and abstract, the villain in is very real and very deadly. Sirius Black, the man who caused the death of Harry's parents, has escaped from Azkaban prison and is apparently after Harry to finish the job he started thirteen years ago. Dementors, the reaper-like creatures who serve as guards for the prison, are sent to Hogwart's School of Witchcraft and Wizardry to protect the school and the students, but the guards themselves are every bit as fearsome as their escaped prisoner.

Of course, Harry doesn't have to go up against Black alone. In addition to his friends Ron Weasley and Hermione Granger, and Hogwart's groundskeeper Hagrid, new Defense Against the Dark Arts teacher Remus Lupin takes Harry under his wing by serving as mentor and confidant.

The three teenage leads (Daniel Radcliffe, Rupert Grint, and Emma Watson) have grown into these roles quite nicely, and along the way developed into fine actors. Radcliffe is necessarily angrier in this film, and the rage Harry feels allows him to give the character far more depth and emotion than we've previously seen. Without much to do, Grint is often relegated to mugging for the camera, though his few moments of humanity stand out as some of the film's truest scenes. Watson, likely the best actor of the three, really comes into her own, also delivering a more nuanced performance for the third installment.