Harry Potter and the prisoner of azkaban

This book is about harry potter and his three friends. Harry is found to be Sirius Black's nephew. But Sirius black is in a prison called Azkaban. Sirius has a bad rep because he is/was a death eater. Once a death eater always a death eater. But Harry doesn't find out until he is warned about Sirius Black. He thinks he killed his parents somehow he think that Sirius rated them out. He on;y finds out that just maybe series is family. He goes on a journey to kill series. Do you think he will? Read to find out?