In this book, the author's tell about Harry and Sirius Black. Harry know Sirius Black from newspaper, he just know that Black is prisioner from Azkaban. Black has killed 13 muggle and 1 witch.
Finally, Harry, Ron, and Hermione met Black. There, in the Dedalu Room's Black told all the story. Black said, He never want to killed Harry Family, and he never to be a spy from Vodermort. Balck told, that who told all the place Potter family is Pettigrew, another friend. And now, Pettigrew is Scabers (Ron Rat).
First, Harry unbelieved Black, but after Black gave proof if Pettigrew is Scabers Harry believed it.
The end, Harry and Hermione help Black to run out from Dementor. Black run out with Buckbeak.
Before Black run out, he said that he is Harry guardian.
