Emboldened by the return of Lord Voldemort, the Death Eaters are wreaking havoc in both the Muggle and wizarding worlds. Hogwarts, once thought to be a safe haven, may no longer be safe. Harry suspects that new dangers may lie within the castle, but Dumbledore is mor intent upon preparing him for the final battle that he knows is fast approaching. Harry will have to help him uncover a vital key to unlocking Voldermort's defenses, a critical piece of information known only to Horace Slughorn, Hogwarts' former Potions Professor. Dumbledore manipulates his old collegue into returning to his previous post with promises of more money, a bigger officeand the chance to teach the famous Harry Potter.