Harry Potter and the Prisoner of Azkaban begins similar to the last two. Harry (Daniel Radcliffe) is living with his Aunt (Fiona Shaw) and Uncle (Richard Griffiths), however this time they're being visited by his Uncle's nasty sister, Marge (Pam Ferris). Harry, however, is done putting up with them, and for the first time in his life he fights fire with fire, right before leaving for Hogwarts for the year. Upon leaving, he, of course, meets up with Ron (Rupert Grint) and Hermione (Emma Watson), and while on the express, Harry is informed about a murderer on the loose named Sirius Black (Gary Oldman), who just may be responsible for his parent's deaths. The man recently escaped from Azkaban Prison, one of the hardest prisons to escape from, and is on the hunt for Harry, who vows to do whatever it takes, including fend off the horrifying Dementors surrounding Hogwarts, to defeat Sirius Black.
In terms of tone, The Prisoner of Azkaban nails it. It's by far the darkest of the first three. and yet it's also the funniest. This film gets scary. No, seriously. The first time we meet the dementors was a chilling, highly suspenseful sequence. Every time those damn things are on screen I was rather unsettled. This film isn't The Conjuring, so it won't cause nightmares, but it is nice that they cheapen the film with non-threatening monsters. I laughed more in this one than in the other two films combined. It's just funny, there's nothing else to really say, especially Ron, who stood out here far more than in the other films. The style on display is so fine tuned and it really sets itself apart from the earlier movies. It also changes the structure up, making it something other than just the same film over and over, much like Chamber of Secrets (and it's 20 minutes shorter).
Speaking of that final sequence, the action in general is very well filmed. From the scene on the Bus early on to the very exciting Quidditch sequence, the action looks phenomenal and is just a ton of fun. And there's a lot of it, so the run time goes by in the blink of an eye. The special effects, as well, continue to improve. They're not perfect, but there are times where they look like they're from a modern day movie. But that Quidditch scene I mentioned looks leaps and bounds better than in the previous two. This film is just a joy to look at, and I may sound like a broken record, but I don't care. It's cinematic eye candy, and I loved it. There's a sequence in a hallway that just consists of two people talking, but it's shot in such a cool way, gripping me as thought it was an action scene or something just as big and grand.