harry potter and the prisiner of azkaban by j.k. rowling

Long years, the dread fortress of azkaban held an infamous prisoner named Sirius black. Convicted of killing 13 people with a single curse, he was said to the heir apparent to the dark lord, Voldemort.

Now he has escaped, leaving only two clues as to where he might be headed: Harry Potter's

defeat of you- know- who was blacks downfall as well. And the azkaban guards heard black muttering in his sleep he's at Hogwarts ...he's at Hogwarts

Harry Potter is not safe not even within the walls of his magical school, surrounded by his friends. Because on top of it all, there may well be a traitor in there midst.