For anyone who hasn't seen the previous films or read the books, this is the third instalment in the Harry Potter series and deals with the titular hero's third year at Hogwarts School of Witchcraft and Wizardry. There are some necessary plot details included, but for anyone who hasn't seen the film, the ending is not spoiled in any way.

Plot Synopsis

As with the other two films, this follows the original book fairly closely, within the constraints of the two and a half hour running time. The opening scenes see Harry (Daniel Radcliffe) at the Dursleys' awaiting the arrival of the hideous Aunt Marge (Pam Ferris). She wastes little time in telling Harry how bad she thinks his parents were. Harry snaps and makes her inflate in a scene that is grotesque and funny in equal measure.

Harry makes his escape from Privet Drive and sees a huge black dog watching him. After an entertaining five minutes on the Knight Bus, which is a tour de force of humour and special effects, Harry arrives in London to be met by a relieved Cornelius Fudge (Robert Hardy). He finds out that Sirius Black (Gary Oldman), an infamous murderer, has escaped from the wizard prison Azkaban and is apparently looking for him.

On the Hogwarts Express Harry, Ron (Rupert Grint) and Hermione (Emma Watson) face the Dementors, horrible creatures who feed off the good memories of wizards leaving only bad ones, who are searching the train for Black. Because of the horrors in Harry's past he is the worst affected of the students, leading to sarcastic comments from Draco Malfoy (Tom Felton) and his friends. He is helped by the new Defence Against the Dark Arts teacher Remus Lupin (David Thewlis) who teaches him the Patronus charm.

Strange events are occurring at the school. For instance, Hermione is turning up in classes without being seen by anyone else, much to Ron's discomfort, while Sirius Black is finding a way to sneak into Hogwarts unobserved. Draco feigns serious injury after ignoring Hagrid's advice about the polite way to greet a hippogriff, a magical creature that is half-eagle and half-horse. Due to this, the hippogriff is sentenced to death, and, in the most replayed scene of the film, Hermione punches Malfoy by way of retribution. By the end of a tumultuous day Sirius Black has been recaptured and prepared for punishment, despite Harry's belief in his innocence. Dumbledore (Michael Gambon) can do nothing through official channels, but he reminds Hermione that she has the power to save the day. When she reveals her secret, Hermione and Harry embark upon a dangerous rescue mission that has only a slim chance of success.

A New Director

Alfonso Cuaron takes over directing duties from Chris Columbus who was at the helm for the first two films. Columbus was a safe pair of hands, but in handing over the reins to a new director, the series could be taken in a different direction. It would have been understandable for Cuaron to avoid changing a successful formula. Instead he has made significant changes showing a great confidence and flair. Whereas Columbus, with his background in formulaic family films, gave us a bright theme park for the stories, Cuaron brings in a truly gothic feel that makes the world of Harry Potter much more threatening. Hogwarts itself has been changed into a dark, haunted castle with new shocks around every corner. The Dementors are a marvellous creation, and one can imagine less skilled directors over-using them. However, Cuaron manages to keep every appearance as shocking as the last by only introducing them when they are absolutely central to the plot. Even the pictures seem less content to stay in the background as they bark out orders and comment on the action like a Renaissance version of the Greek chorus. The students look more like normal teenagers, as their robes and school uniforms are replaced by jeans and sweatshirts. This has not been universally popular, but the contrast between the gothic and the modern day helps to make the young actors more relevant, and less like refugees from a British period piece. Cuaron has gone on record as saying that he had never read the books before embarking upon this film and it shows. The fresh eye that he brings to the film means that devotees of JK Rowling's books are encouraged to discover the young magician anew. As he hands over to Mike Newell for Goblet of Fire, he can reflect on a job well done.

Harry, Ron and Hermione

As required by the books, the three young leads shoulder much of the screen time. Their progression since the second film is quite astounding, both in physical terms and in acting terms. Daniel Radcliffe lets himself inhabit the character for the first time. Gone are the stiff, clipped speeches of the first two films. In their place are expressions of real anger and frustration that make him instantly recognisable as a teenager from any generation. He is more heroic during the action sequences, as the young boy overwhelmed by events is replaced by a proactive and aggressive young man. For the first time the audience can see the inner power that allowed Harry Potter to stop Voldemort. We do not know what that power is, any more than Harry does, but its presence is now obvious.

Rupert Grint is arguably the most improved of the three young actors. His characterisation of Ron in the first two films was generally regarded as being almost entirely made up of face-pulling and vocal acrobatics that added little to the scenes. Here, Cuaron has teased out a far more restrained and effective performance that balances up the relationships between the three main characters. His performance in the scene with Scabbers when Ron finds out the true nature of his rat are extremely well played. Clearly the effect of playing opposite the cream of British acting in one room rubbed off on him. From being a clear second best to Harry and Hermione, Ron is now an integral member of the team of three heroes.

Emma Watson is, by common consent, the standout of the three main characters. Her performances have grown more assured as the series has progressed and in this film she is, in the opinion of most critics, nothing short of brilliant. One even described her as being a young Grace Kelly. Hermione is now a multi-layered character rather than a brainy bookworm. Her dishing out of retribution to Malfoy shows a real spirit and anger that has only been hinted at before. When she is required to display real bravery she is not found lacking. Cuaron hints at Hermione's blossoming, as Emma Watson herself acknowledged in interviews, by allowing her to dress in more fashionable clothes. Despite this, the pivotal ball scene in fourth book Goblet of Fire has been prepared for extremely well. If Cuaron had kept the plain Hermione of the earlier films, the transformation would be unbelievable. If, on the other hand, he had made her blossoming explicit, the transformation would have been much less effective. There is a great line later in the film when she makes a disparaging comment about her own hairstyle. Emma Watson is already being spoken of as a great actress in the making and this film gives ample evidence to support that view.

The Supporting Cast

The performances of actors like David Thewlis, Gary Oldman and Alan Rickman give the film its real soul and power. The way that they trade lines off of each other is fantastic to watch. Snape really comes into his own during this film, but he is more than matched by his old nemeses Lupin and Black. His hatred of the pair hints at a sub-plot that is slowly being developed in the series, but once again more questions are asked than answered where Snape is concerned. Michael Gambon does a fine job as replacement for Richard Harris by taking his characterisation of Albus Dumbledore as a model and adding a few touches of his own. As ever, Robbie Coltrane is a strong reassuring presence as Hagrid, stealing every scene he's in.

This is a more grown-up Harry Potter, but it's still a magical film for children. In many ways it has redefined the books, while still remaining true to their spirit. The improvement on the first two films is marked, as arguably the best book in the series so far has been made into the best film.