When Harry Potter and the Half-Blood Prince opens, the war against Voldemort has begun. The Wizarding world has split down the middle, and as the casualties mount, the effects even spill over onto the Muggles. Dumbledore is away from Hogwarts for long periods, and the Order of the Phoenix has suffered grievous losses. And yet, as in all wars, life goes on. Harry, Ron, and Hermione, having passed their O.W.L. level exams, start on their specialist N.E.W.T. courses. Sixth-year students learn to A