with his best friends Ron Weasley and Hermione Granger. In Diagon Alley, they see Draco and Narcissa Malfoy, and follow them into Knockturn Alley. The pair meet with Death Eaters, including the werewolf Fenrir Greyback, at Borgin & Burke's. Harry believes Draco is now a Death Eater, but Ron and Hermione are sceptical. On the Hogwarts Express, Harry sneaks into the Slytherin carriage wearing his Invisibility Cloak to spy on Malfoy. Malfoy notices and petrifies Harry, leaving him on the train. Luna Lovegood finds him and counters Draco's spell. Harry discovers that his used Potions textbook is filled with helpful notes and spells added by the "Half-Blood Prince". Using it, Harry excels in class, annoying Hermione and impressing Slughorn, who awards him a Liquid Luck potion. Ron makes the Gryffindor Quidditch team as Keeper and begins dating Lavender Brown, upsetting Hermione. Harry consoles Hermione while acknowledging his own feelings for Ginny Weasley. Harry spends the Christmas holidays with the Weasleys. His suspicions about Draco are dismissed by the Order, but Arthur Weasley reveals that the Malfoys may be interested in a Vanishing Cabinet at Borgin & Burke's. Bellatrix and Greyback attack and destroy the Burrow. At Hogwarts, Dumbledore asks Harry to retrieve Slughorn's memory of a young Voldemort. Slughorn has resisted giving an accurate memory. After Ron accidentally ingests a love potion intended for Harry, Harry takes him to Slughorn for a cure. Slughorn offers the boys some mead he had intended as a gift to Dumbledore. Ron is poisoned upon sipping it. Harry's quick thinking saves Ron. While recovering in the infirmary, Ron murmurs Hermione's name, causing Lavender to end their relationship. Harry confronts Draco about the poisoned mead and also a cursed necklace that nearly killed Katie Bell. A duel erupts, and Harry uses one of the Half-Blood Prince's curses without knowing what it is. The curse severely injures Malfoy, and he is only saved by Snape's timely arrival and reversal of the curse. Fearing the book contains Dark Magic, Ginny persuades Harry to hide it in the Room of Requirement. They then share their first kiss. Harry uses his Liquid Luck potion to convince the reluctant Slughorn to surrender the memory Dumbledore needs. Viewing it in the Penseive, Dumbledore and Harry learn Voldemort sought information about Horcruxes, magical objects containing pieces of a wizard's soul for immortality. Dumbledore surmises Voldemort divided his soul into six Horcruxes, two