The third book in the bestselling Harry Potter series now illustrated in glorious full color by award-winning artist Jim Kay! For twelve long years the dread fortress of Azkaban held an infamous prisoner named Sirius Black. Convicted of killing thirteen people with a single curse he was said to be 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 Black s downfall as well. And the Azkaban guards heard Black muttering in his sleep He s at Hogwarts . . . he s at Hogwarts. Harry Potter isn t 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 their midst.