If you enjoyed the first two movies, be warned: There are plenty of differences in this third installment. With a new director on board (Alfonso Cuaron), the tone of the series has shifted somewhat, to a darker, more serious Harry Potter universe.

If you’ve read the books, you should also be warned: There’s a lot of stuff in the third book that doesn’t appear in the third movie. Part of this is out of necessity, as this film is a bit shorter than the first two (while the book is longer), but even so there are characters from the book who don’t appear in the movie and story threads that aren’t satisfactorily resolved.

The crux of the story is that the man who led Lord Voldemort to Harry’s parents, Sirius Black, has escaped from Azkaban Prison, presumably to hunt down the offspring of his onetime close friends – and kill him! The guards at Azkaban, the Dementors, are out in full force to track down Black and return him to prison. Ah, but these are no ordinary guards; the Dementors – dark, faceless beings in black cloaks – feed off a person’s emotions, eventually sucking their soul out, rending them helpless. The Dementors personify depression in the extreme, you see.

Harry first encounters the Dementors on the way to school aboard the Hogwarts Express as they search the train for Black. It’s not an enjoyable encounter for the boy wizard, who faints dead away. Later, at the school, it’s learned that Black is getting closer and closer. Will he find Harry?

New to the faculty at Hogwarts are Remus Lupin as the Defense Against the Dark Arts professor (a position that is empty at the end of each book) and Sybil Trelawney as the Divination professor. Both figured into the plot of the book, but only Lupin gets any real screen time in the movie. Lupin, played with effortless panache by David Thewlis, winds up being a confidante of Harry, and he has more than a few secrets in his closet as well. Also, taking the place of the late Richard Harris as Headmaster Dumbledore is Michael Gambon, while Rubeus Hagrid (Robbie Coltrane) is promoted to the position of
professor.

There are two main plotlines at work here: the anticipation of the arrival of Black and the revelations of the circumstances surrounding the deaths of Harry’s parents. We learned a bit at the end of each of the first two HP films, and this one too takes its sweet time in clueing us all in.

A new director and tone can lead to some dangerous uncharted waters, and expectations must be tempered somewhat. Please do not go to this movie expecting the charm of the first two; this is not your older brother’s HP. As Harry himself matures, so must his movies, and this one is more cynical and downbeat at times than either of the first two in the series. This matches, at least somewhat, the tenor of the third book itself.

Cuaron’s direction is excellent, and his little touches are abundant (such as the rearranging of the Hogwarts grounds, the use of the Whomping Willow as a device to show time, and endless presence of a giant outdoor clock). The movie doesn’t lag too much, although it’s possible that a newcomer to the HP oeuvre might not pick up all of the plot threads.

The cast does a good job, I think, in maintaining the spirit of the previous movies and books. The young lead trio (Daniel Radcliffe, Rupert Grint, and Emma Watson) are aging quite well; in fact, I think Watson is becoming quite a wonderful young actress. (Grint, by the way, holds his hamminess down to a dull roar.)

They’re well supported, of course, by a who’s who of master British thespians, from Thompson to Thewlis to Alan Rickman (still delightfully creepy as Snape) to Gambon to Maggie Smith to Coltrane. Any British actor who’s anyone wants to be in these movies, and that’s high praise indeed.

The special effects, too, aren’t second rate. Buckbeack the hippogriff looked positively realistic (although Crookshanks the cat looked laughable).

HP:PoA is well worth watching, especially if you have little munchkins in your household who have been clamoring for it since the last Harry Potter movie. But beware, there are some scenes that the younguns may find a bit more unsettling than either of the first two movies.

Harry Potter and the Prisoner of Azkaban: ***1/2