The death of Harry Potter’s godfather, Sirius Black, has made Harry more grown up than ever before. Now he feels that he has to put an end to Voldemort’s reign of terror, even if it kills him. Dumbledore picks Harry up before the end of summer to go on a mystery errand. The errand is to get Horace Slughorn to teach again at Hogwarts. Back at Hogwarts for Harry’s sixth year, he is extremely excited. He is now the Quidditch team captain. However, Harry also finds out and is gloomy that Professor Snape has achieved his longtime goal of being the Defense Against the Dark Arts teacher. Harry has also started taking private lessons with Dumbledore to learn as much about Voldemort as he can. Hopefully this information will help if Harry ever comes face to face with Voldemort. Early on in Harry’s Potions class he acquires a mysterious book that used to be the Half Blood Prince’s. The book tells Harry everything he needs to know about potions. Harry’s sudden knowledge amazes everyone. He also grows a suspicion that Draco Malfoy has replaced his father as the leader of the Death Eaters. Harry, throughout the year, keeps a close eye on Draco just in case. Ron and Hermione see this idea as a far stretch, but Harry feels like something has to be happening with Draco frequently leaving school grounds. As the year continues, Dumbledore tells Harry that he may be able to go on a special mission to destroy a horcrux. A horcrux is an item that contains a part of Voldemort’s soul. Destroying them makes Voldemort weaker. When Harry and Voldemort leave on their mission to destroy the horcrux, Draco sneaks Death Eaters into the school, and a battle between the Order of the Phoenix and the Death Eaters takes place. Harry and Dumbledore return after getting the horcrux, but they are trapped on the Astronomy Tower. On the Tower, Draco disarms Dumbledore and Professor Snape kills him. Dumbledore’s death had a massive impact on Harry, but it helped him to see what he had to do.