J. K. Rowling - Harry Potter and the Half-blood Prince

Packed with mystery, subterfuge, and a more intimate understanding of the challenges that lie ahead of him, Harry Potter's sixth year at Hogwarts heaves with his growing sense of responsibility regarding the defeat of Lord Voldemort, a relentlessly sneaking suspicion that classmate Draco Malfoy is a Death Eater in cahoots with the dastardly Professor Snape, and a host of romantic entanglements that hilariously plague everyone. Harry's busy N.E.W.T.-level schedule includes Potions, where he surprises himself by excelling due to strangely helpful, hand-written margin notes in his book, ascribed only to the enigmatic "Half-Blood Prince." Sporadic, private lessons with Dumbledore center on the personal history of Lord Voldemort, which both unnerves and fascinates Harry. At the same time, the romantic ups and downs of Ron and Hermione threaten to destroy their friendship. The sixth installation in the phenomenally successful Harry Potter series opened with record-breaking sales of an estimated 6.9 million books