A brief sojourn in suburban misery and Harry is back for his third year at Hogwarts, a year that will turn out to be no less of a life-threatening adventure than the previous two. Harry discovers that Sirius Black, a man he believes is in league with his arch-enemy, has escaped from prison and talk at the school is that Sirius is determined to hunt Harry down and finish the job his mentor started. 'Harry Potter and The Prisoner of Azkaban' has all the blemishless CGI we have come to expect, along with the wraithlike Dementors, bad tempered trees and eagle horsey things. It's a darker film than the first two and makes the parental guidance certificate well worth heeding if the little nippers are going to be watching.