When it hit shelves: July 16, 2005
What happens in the book: No longer able to deny Voldemort's return as the Dark Lord and his minions wreak havoc in both magic and Muggle communities the Minster of Magic, Cornelius Fudge, resigns. Arthur Weasley is promoted to Head of Detection and Confiscation of Counterfeit Defensive Spells and Protective Objects, and the Weasleys' financial situation improves.
On the dark side of the world, Draco Malfoy's mother makes Snape swear he will protect Draco. To everyone's surprise, Snape takes a post he has long coveted: professor of Defense Against the Dark Arts. Meanwhile, emotions between Harry, Ron and Hermione are at an all-time high when Ron starts dating Lavender. Harry is caught between Ron and Hermione's cross fire, which doesn't end until Ron is poisoned.
Dumbledore shares with Harry his theory that Voldemort's soul was split into seven parts, called Horcruxes, to attain immortality. If all his Horcruxes are destroyed, Voldemort is a goner for good. Dumbledore and Harry review all the memories about Voldemort that Dumbledore has collected in order to figure out where the Horcruxes might be located.
Harry and Dumbledore seek out the third Horcrux. Upon their return, Voldemort's Dark Mark looms over Hogwarts the Death Eaters have infiltrated the school. Draco is ordered to kill Dumbledore but hesitates, so Snape performs the killing instead. Dumbledore's Army defends the campus until the Order of the Phoenix arrives to give chase to the Death Eaters. The Horcrux in Harry's possession turns out to be a fake.
The students, professors and ghosts at Hogwarts are immensely saddened by Dumbledore's death. There is talk of closing down the school for good. Harry ends his budding romance with Ginny to protect her from Voldemort. Harry also decides to leave Hogwarts, and vows to find the remaining four Horcruxes with Ron and Hermione's help.
Ginny Weasley: Sister to Ron, confidant to Hermione and newfound love interest to Harry. After a brief relationship yes, they snogged Harry tells Ginny they can't be together for her safety
Horace Slughorn: Back from retirement as Potions professor. Dumbledore challenges Harry to retreive a crucial memory from Slughorn that of young Voldemort and Horcruxes
Narcissa Malfoy: Draco's mother. She makes Snape swear that he will protect Draco
Rufus Scrimgeour: Appointed as the new Minister of Magic. He tries to enlist Harry as a source of morale for the wizarding community during these dark times, but Harry refuses to be used by the Ministry of Magic in this way
The Magic Gadgets:
Felix Felicis: Lucky liquid, it grants good luck to the drinker temporarily. Harry "earns" a small vile of Felix and gives it to Ginny, Ron and Hermione so they can be lucky when the Death Eaters infiltrate Hogwarts
Vanishing Cabinet: Transfers contents to its sister cabinet. Death Eaters penetrate Hogwarts through a tunnel between Hogwarts' Vanishing Cabinet and its pair in the seedy Knockturn Alley store, Borgin and Burkes
Horcrux: A dark magical receptacle in which one places a fragment of his soul in order to attain immortality. Voldemort is believed to have created seven Horcruxes