The film opens with a rather heartbroken Harry Potter, haunted by the death of Cedric Diggory and the rise of Voldemort. The Ministry of Magic has worked very hard to portray Harry and Dumbledore as crackpots. Confronted by cousin Dudley and his friends, Harry becomes angry with Dudley and pulls his wand on him. This is a nicely acted scene, as the moment Dudley sees the wand, his expression goes from cocky to scared (while his friends all laugh, having no idea Harry is a wizard).
The skies go dark and Harry finds he and Dudley under an attack from Dementors. Harry fights off the Dementors, but this results in his being expelled from Hogwarts for being an underage wizard using spells off campus. Harry must face a brief hearing to address if he will be punished. Dumbledore prevents this from being permanent.
Harry is also frustrated by the fact that nobody has been in contact with him. He discovers that Dumbledore has brought together several people to form the Order of the Phoenix. It includes Lupin, the Weasleys, Sirius Black, Mad-Eye Moody and shockingly to Harry, Professor Snape.
Once back at Hogwarts, the kids are introduced to the new professor of Defense Against the Dark Arts. Delores Umbridge is really there as an eye for the Ministry of Magic, which does not trust Dumbledore. She does not teach the children spells. Instead, she focuses on books, arguing the children will never need to put such things into action.
Umbridge slowly takes over the school, enforcing ridiculous and endless rules. She forces out Dumbledore, inspiring Harry to bring together like-minded students to prepare to fight Voldemort.
this is the heart of the film, as Harry and his friends strive to prepare for the coming battle. But Harry also struggles with nightmarish visions, some of which turn out to be true. This causes him to believe Sirius is in great danger, causing Harry and a few members of his class to set out to save Sirius by breaking into the Ministry of Magic’s archives department. This leads to an all-out battle royale.
Order of the Phoenix is notable as being the only Harry Potter Film without a Steve Kloves screenplay. And in some ways, this film feels the least connected. It also suffers from issues like setups not being addressed. It never explains the Dementor attack.
Certainly, we can assume it was due to Voldemort or even the Ministry of Magic…but while the event is questioned, it is never answered.
Still, this is a generally good film within the franchise, even if we only get glimpses of characters like Sirius Black (blunting his overall impact). The introduction of Bellatrix LeStrange (played with gleeful delirium by Helena Bonham Carter) and Luna Lovegood (who, in some ways is a sweetly natured reflection of LeStrange) are welcome. Imelda Staunton makes Delores Umbridge gloriously hateable.
The film also introduces one of my favorite characters from the books, Tonks. She is kind of what I figure a young and modern witch or wizard would be like (for example, using magic change hair color and styles).
This film brings on David Yates as director and visionary for the rest of the series (under the watch of Rowling and Kloves). Primarily a television director, Yates acquits himself quite well in this big budget picture.