Lord Voldemort has returned to power, and
his wrath has been felt in both the Muggle and Wizarding worlds. Severus
Snape, long considered an enemy of Voldemort and a member of Dumbledore’s
anti-Voldemort coalition, the Order of the Phoenix, meets with Narcissa
Malfoy, mother of Draco and wife of Lucius, an imprisoned Death Eater.
Snape makes an Unbreakable Vow to Narcissa, promising to protect
her son, Draco.
Dumbledore heads to 4 Privet Drive
to collect Harry from his aunt and uncle. On their way to the Burrow,
Harry and Dumbledore stop to recruit Horace Slughorn to return to
teaching at Hogwarts. Harry is reunited with his best friends, Ron
and Hermione. When shopping for schoolbooks, Harry runs into Draco
and follows him to Borgin and Burkes, where he overhears Draco threatening
Borgin and insisting that he fix an unknown object. Harry is instantly
suspicious of Draco, whom he believes to be a Death Eater, just
like his father. The students return to school, and Dumbledore announces that
Snape will be teaching Defense Against the Dark Arts, much to Harry’s
surprise.
Harry receives a used Potions textbook that once belonged
to someone named “The Half-Blood Prince.” Spells and amendments are
written in the margins of the book, and Harry uses the Prince’s notes
to excel at Potions. Dumbledore schedules regular meetings with
Harry in which they use Dumbledore’s pensieve to look at memories
of those who have had direct contact with Voldemort. Dumbledore
believes that if Harry can learn enough about Voldemort’s history,
it will help him when they finally fight face to face, as the prophecy
concerning Harry foretells. Harry learns about Voldemort’s family,
including his grandfather Marvolo, his uncle Morfin, and his mother
Merope, who cast a love spell on a Muggle and was abandoned by him
when it wore off. Voldemort was left at an orphanage and grew to
be an unpleasant and aggressive boy. Harry also learns that Voldemort
has divided his soul into seven Horcruxes. Two of these, Tom Riddle’s
diary and Marvolo’s ring, have already been destroyed. One resides
in Voldemort, one resides in a snake, one is Merope’s locket, and
the other two are suspected to be hidden in objects belonging to
Hufflepuff, Ravenclaw, or Gryffindor.
Ron acquires a new girlfriend, Lavender, of whom Hermione
is extremely jealous. Harry feels stuck in the middle of his friends’ bickering.
Eventually, Harry falls in love with Ginny, Ron’s sister, and Ron
and Lavender break up, making Hermione quite happy. Harry spends
much of his time keeping up with his duties as Quidditch captain
and following Draco Malfoy. Harry uses his Marauder’s Map to keep
track of Draco, but often cannot find him on the map. Eventually,
Harry realizes that when Draco is not on the map, he is using the
Room of Requirement on the seventh floor of Hogwarts, which transforms
into whatever its user needs. Harry tries his best to get in to
see what Draco is up to, but until he knows exactly what Draco is
using the room for, he cannot gain access. Eventually Harry and
Dumbledore leave Hogwarts together to fetch and destroy Merope’s
locket, thus making Voldemort one step closer to mortal. They must
overcome a variety of traps and challenges before reaching the basin
where the locket is hidden under a poisonous potion. Dumbledore
drinks the potion and Harry fights off Voldemort’s Inferi. They
take the locket and return to Hogwarts as quickly as possible. Dumbledore
is quite weak, and when they reach Hogsmeade they can see that the
Dark Mark is visible above the astronomy tower.
Harry and Dumbledore rush toward the tower. When they arrive,
Dumbledore uses his magic to freeze Harry in place, while Harry
remains hidden by his cloak of invisibility. Draco Malfoy sprints
into the room, threatening Dumbledore’s life. Weak and with his
wand out of reach, Dumbledore stalls Draco, telling him that he
is not a killer and that the Order of the Phoenix could protect him
and his mother from Voldemort. Draco lowers his wand, and Snape
pushes into the tower. Harry cannot move or speak, but he hears
members of the Order fighting Death Eaters below. Snape raises his
wand and kills Dumbledore, sending him flying over the edge of the
tower. When Dumbledore dies, his spell on Harry is broken, and Harry
rushes after Snape, determined to avenge the death of his friend
and headmaster. Snape escapes, and Harry is devastated. He looks
at the locket he and Dumbledore retrieved and realizes that it is
not a Horcrux. Inside the locket is a note from someone named “R.
A. B.” Harry tells his friends he will not be returning to Hogwarts
next year and will instead search out and kill Voldemort by destroying
all of the Horcruxes. Ron and Hermione vow to join him.