Harry blows up aunt marge then discover Siruis black a crimnal wants to kill him he is supposed to be the servant of lord Voldermort But it turns out to be Peter who sold his Parents to Voldermort. He ends up facing black while Lupin turns out to be a werewolf and an old freind of harrys father as well it turns out Scarbers is Peter but he faked his own death and pretends Croshanks killed him. Hermonie then find out his hiding in hagrids kettle probaly the best harry potter book.