Harry, Ron and Hermione return for their third year at Hogwarts, and my, haven't they grown... The third film - and many would argue the best - follows the story of the dangerous and enigmatic wizard Sirius Black (Gary Oldman), who has escaped Azkaban prison and is apparently determined to kill Harry. Director Alfonso Cuaron darkens the tone, assisted by a legion of scary Dementors.
Hermione's tweedy A-line skirts and knitted jumpers - gone! The unpredictable vocal warblings of pre-pubescence - gone! The sense that really and truly you're watching a kids film - gone!
Yes, director Alfonso Cuaron and the team have certainly pulled the ace out of the pointy wizard's hat to produce the metaphorical white bunny of triumph.
This is the darkest, funniest, and most accomplished Harry Potter yet.
It transpires that a dangerous and enigmatic wizard Sirius Black has escaped Azkaban prison and is determined to kill Harry.
According to legend, Black was responsible for leading Voldemort to Harry's parents and ultimately to their deaths.
For the schools security, Hogwarts plays host to the sinister Azkaban guards, the Dementors, who are positioned at the school in an attempt to protect the students (and more specifically Harry) from Sirius Black.
As well as the wraithlike Dementors, the film introduces a host of new magnificently sinister CGI creatures.
These include a Hippogriff (that's half-horse half-eagle before you start trying to imagine some sort of airborne hippo) and a chillingly bald werewolf complete with protruding spinal column and long skeletal limbs (eurgh).
The once board-like performances from the cast of child actors have been honed into a much less stilted, much more plausible version of a rabble of school kids, with uniforms and personalities more akin to the authentic swarms of hoarding bus travellers we know and love as our own rapscallions.
Michael Gambon proves he's the very person to fill the eminent wizard's slippers of the late great Richard Harris, with an excellent performance as esteemed Headmaster Albus Dumbledore.
Emma Thompson plays a salaciously ironic near-sighted yet prophetic Professor of Divination, whilst elsewhere the film bursts at the seams with cameos from the very best of British film and theatre.
Newcomers to the world of Harry Potter, Timothy Spall, Julie Christie, Pam Ferris, and of course Gary Oldman as the murderous Sirius Black, as well as the much loved and well established characters of the last two films, all have a tremendous hand in making this the best yet.