When Harry (Daniel Radcliffe) accidentally causes his Aunt Marge (Pam Ferris) to fill up with helium and float away, he fears he will be expelled from school (especially after the previous years' Dobby incident). After a quick packing, he storms out of the house on Privet Drive and inadvertently calls the Night Bus. While on the magical bus, Harry gets his first glance at this story's menace. It seems that Voldemort's top henchman, Sirius Black (Gary Oldman) has broken out of the Wizarding Prison of Azkaban, a feat never before accomplished.
To make matters worse, it appears that Black has broken out to hunt down and kill Harry. When Harry learns that Black was once his parents' best friend and he is the one that betrayed his parents to the Dark Lord, Harry's common sense gets flushed down the tubes and his desire for revenge takes hold. Unfortunately, Harry has other problems to worry about, namely, Azkaban's guards, creatures called dementors.
The evil creatures are being housed at Hogwarts in order to look for Black, and while most of the kids don't feel too many ill effects by their presence, Ron (Rupert Grint) and Hermione (Emma Watson) included, Harry has a tendency to pass out. It turns out, the dementors make great guards because they suck all of the happiness from you and force you to relive your worst memories. For most Hogwarts students, this isn't anything too bad, but considering Harry's dealings with Voldemort and his parents' death, he has a lot of bad events to relive.
Thankfully, Harry has the help of the new Defense Against the Dark Arts teacher, Professor Lupin (David Thewlis). This scrawny teacher ends up quickly becoming all of the student's favorite as he prefers the hands-on approach, but never to such a dreadful result as the previous year's Professor Lockhart (Kenneth Branagh). With the help of Lupin, Harry learns a new spell that creates a silver shield of warmth to protect himself from the dementors and their soul-stealing kiss.
Meanwhile, Hagrid (Robbie Coltrane) has gotten a promotion and become the school's new Care of Magical Creatures teacher, and boy does he have a bunch of unusual beasts to show his class. Hagrid's story is a bit of a side-arc in this movie, but ultimately plays a pivotal part in the overall film. When he introduces a Hippogriff (a half-eagle, half-horse creature) to the class, Draco Malfoy (Tom Felton), gets hurt and it looks like Buckbeak, the Hippogriff, might be put to death.
While the book version of Prisoner of Azkaban is one of my favorites in the series, the film just doesn't seem to pack as much of a punch. There are a lot of details missing, and while that can be said of most book-to-movies, especially Harry Potter ones, this particular film seems to leave off a lot. That being said, the Ultimate Edition does seem to add a few of those tidbits back, which helps a good bit.
This Ultimate Edition offers a few more goodies as well. The biggest being the third-installment of the massive documentary that spreads across all of these releases. This time, the documentary focuses on the various creatures from the series and you get to learn about everything from their conception to their implementation. I found this particular feature to be the most interesting one yet.
Harry Potter and the Prisoner of Azkaban Ultimate Edition also comes with the normal slew of making-ofs and games, but the real centerpiece is the added footage to the film, the high-definition visuals and the Creatures documentary. This, combined with all of the special features from the previous home releases, makes the Ultimate Edition a very appealing purchase. The only thing I find missing is a copy of the theatrical release like the first two Ultimate Editions had. Then it would be the perfect replacement for any existing copies of this film that you might already have.