<P> Harry spends the Christmas holidays with the Weasleys . On Christmas Eve, Harry discusses his suspicions about Draco to the Order of the Phoenix . Harry's suspicions are dismissed by the Order, but later on Arthur Weasley tells Harry privately that the Malfoys may have been interested in a Vanishing Cabinet . Bellatrix and Greyback attack the Burrow and burn it down, drawing Harry into a battle, trying to save Ginny, before the Order arrive and fight them off . At Hogwarts, Dumbledore reveals to Harry that Slughorn possesses a memory of Voldemort that Dumbledore needs desperately . Slughorn gave Dumbledore the memory, but it was an altered version that made it appear that Slughorn didn't know anything . Dumbledore shows Harry the altered memory and asks him to confront Slughorn and retrieve the real one, but when Harry brings it up Slughorn gets angry and refuses to talk any more about it . After Ron accidentally ingests a love potion, Harry brings him to Slughorn for a cure and to smooth over their argument from earlier . After curing Ron, the trio celebrate with mead that Slughorn had intended to gift to Dumbledore . The mead poisons Ron, and Harry is forced to save his life after Slughorn hesitates . Ron murmurs Hermione's name while recovering in the infirmary, causing Lavender to end their relationship . Harry confronts Draco about the poisoned mead and a cursed necklace, and the two duel . Harry uses a curse from the Half - Blood Prince's potion book to severely injure Malfoy, who is rescued and healed by Professor Snape . Fearing the potion book may be filled with more Dark Magic, Ginny and Harry hide it in the Room of Requirement and share their first kiss . </P> <P> Harry decides to use his Liquid Luck potion to convince Slughorn to give up the memory Dumbledore needs . Harry views the memory with Dumbledore and learns that Voldemort wanted information for creating Horcruxes, magical objects that could contain pieces of a wizard's soul and save them from death . Dumbledore concludes that Voldemort successfully created seven Horcruxes, two of which have already been destroyed: Tom Riddle's diary and Marvolo Gaunt's ring . Harry and Dumbledore travel to a seaside cave where Harry aids Dumbledore in drinking a potion that hides another Horcrux, Slytherin's locket . A weakened Dumbledore defends them from Inferi and apparates back to Hogwarts . Bellatrix, Greyback, and more Death Eaters enter Hogwarts with Draco's help through the vanishing cabinet in the Room of Requirement that Draco managed to connect to the one he had been working on in Knockturn Alley . </P> <P> Dumbledore instructs Harry to hide and not to interfere no matter what happens . Draco arrives in the Astronomy Tower and disarms Dumbledore revealing that he has been chosen by Voldemort to kill the headmaster . When Draco is unable to bring himself to do it, Snape casts the killing curse instead, killing Dumbledore, who falls from the tower . Harry confronts and attacks Snape, but Snape overpowers him, and reveals himself as the Half - Blood Prince before escaping . Harry returns to Hogwarts, where the students, staff, and a few guests mourn Dumbledore's death . Harry later reveals to Ron and Hermione that the locket Horcrux was a fake . The locket contains a message from "R.A.B.", stating that he has stolen the real Horcrux with the intent of destroying it . Rather than returning for their final year at Hogwarts, the three decide to hold out, and track down the remaining Horcruxes . </P> <Ul> <Li> Daniel Radcliffe as Harry Potter </Li> <Li> Rupert Grint as Ron Weasley, one of Harry's two best friends . </Li> <Li> Emma Watson as Hermione Granger, one of Harry's two best friends . </Li> <Li> Michael Gambon as Albus Dumbledore, the headmaster of Hogwarts . </Li> <Li> Helena Bonham Carter as Bellatrix Lestrange, one of Voldemort's principal Death Eaters and Draco Malfoy's aunt . </Li> <Li> Jim Broadbent as Horace Slughorn, the newly appointed Potions master who held the position before . </Li> <Li> Robbie Coltrane as Rubeus Hagrid, the Hogwarts gamekeeper and Care of Magical Creatures teacher at Hogwarts . </Li> <Li> Warwick Davis as Filius Flitwick, the Charms master and head of Ravenclaw . </Li> <Li> Tom Felton as Draco Malfoy, Harry's rival and recipient of Voldemort's secret mission . </Li> <Li> Alan Rickman as Severus Snape, the former Potions master, current Defence Against the Dark Arts teacher and head of Slytherin . </Li> <Li> Maggie Smith as Minerva McGonagall, the Hogwarts Transfiguration teacher, deputy headmistress and head of Gryffindor . </Li> <Li> Timothy Spall as Peter Pettigrew, the Death Eater who betrayed Harry's parents to Voldemort . Pettigrew has no lines in this film, but appears as a servant at Snape's house . </Li> <Li> David Thewlis as Remus Lupin, a member of the Order of the Phoenix and Harry's ex-Defence Against the Dark Arts teacher . </Li> <Li> Julie Walters as Molly Weasley, the Weasley matriarch and a mother figure to Harry . </Li> </Ul>

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