Harry Potter: The Prisoner of Azkaban is the third movie in the Harry Potter series and is about Harry Potter's third year at Hogwarts school for young wizards and witches. Right before school starts, Harry learns that a man named Sirius Black has escaped from the most heavily guarded place on Earth, Azkaban. Harry soon learns that this man wants to kill Harry, and Harry searches for guidance.
Meanwhile, these dark creatures called Dementors are all over the grounds of Hogwarts searching for Sirius. The Dementors make people feel like all the happiness in the world has been sucked out, and causes people to remember their darkest, worst memories. Because of Harry's depressing, dark past, he looks for guidance from a new Defense Against the Dark Arts teacher named Professor Lupin.
This movie is probably the worst in the Harry Potter series, but yet still manages to be a great movie. Although the ending is somewhat confusing, the rest is very good and this is a well done movie. The fact that this is one of the weaker Harry Potter movies goes to show how great the Harry Potter movies are.