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 BLACKS 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.