Harry Potter and the Half - Blood Prince Harry Potter and the Half - Blood Prince is the the 6th novel / movie in the Harry Potter series . It was started in 2010 and , although other sets like 4842 Hogwarts Castle and 4841 Hogwarts Express have allusions to this movie , the Burrow is the only official set in this subtheme . Similar to Deathly Hallows , LEGO has not made a specified subtheme for this film , yet one set is based on it . It is also featured as a story in . Plot . With Voldemort ' s return now accepted by everyone . Death Eater s are wreaking havoc on Muggles ; destroying the Millennium Bridge , and Wizards ; kidnapping the wandmaker Mr . Ollivander and destroying his Diagon Alley shop . The Death Eaters then burn down the Burrow . Professor Dumbledore has Harry convince Professor Slughorn to return to Hogwarts to teach , and meanwhile Bellatrix Lestrange entreats Professor Snape to enter an Unbreakable Vow with Draco Malfoy ' s mother , Narcissa Malfoy , assuring that he will complete the task assigned to Draco , should Draco fail and that he will protect him and make sure he doesn ' t get hurt . Harry , Ron Weasley , and Hermione Granger , while in Diagon Alley , spot Draco entering Borgin and Burkes and taking part in a ritual with other Death Eaters , and become suspicious of his actions . Harry and Ron take up Potions now that Professor Horace Slughorn , with lower standards than Snape , is teaching the class ; however , as neither was expecting to take the course , they have to find textbooks for themselves in the bookcase . Harry ' s book is annotated with more exact instructions , hints , and improvements scribbled in the margins to the potions , giving him an edge over the other students . Harry finds that it once belonged to the someone who called himself ( or herself as Hermione suggests ) " " The Half - Blood Prince . " " Dumbledore reveals to Harry through the Pensive memories of Tom Riddle ( Voldemort ' s original name ) and instructs Harry to get an important memory out of Slughorn . Harry is able to get the memory from Slughorn , which reveals that Riddle inquired about the creation of Horcruxes , devices that store a portion of the creator ' s soul to allow them to live indefinitely . Dumbledore says that they must track these down and destroy them to make Voldemort mortal and have a chance of defeating him . Meanwhile , Harry is suspicious of Draco and believes him to be behind two indirect attempts on Dumbledore ' s life , both of which failed and nearly resulted in the Deaths of Ron and Katie Bell . Dumbledore and Harry travel to a seaside cliff , and enter a cave where the Horcrux is located . After Dumbledore is forced to drink a torturous potion in order to retrieve the Horcrux , and they are attacked by inferi ( corpses re - animated with Dark magic ) , they recover the Horcrux , a locket , and return to the Astronomy Tower at Hogwarts Castle . However , Draco appears to kill Dumbledore , but is unable to do so . Bellatrix Lestrange , Fenrir Greyback , and other Death Eaters arrive , and join Draco in the tower . Snape silently arrives and then goes upstairs , joining the other Death Eaters , and then casts the killing curse on Dumbledore , throwing him over the side of the tower and killing him . Snape , Draco , and the other Death Eaters depart the school , Bellatrix casts the Dark Mark over the school , and sets fire to Hagrid ' s hut in glee . Harry pursues Snape in anger , and tries to attack him , but is knocked aside easily . As Snape departs , he explains to Harry that he is " " The Half - Blood Prince . " " Harry returns to the school to find the staff and students mourning over Dumbledore ' s death . The Horcrux they obtained was a fake , containing a message from an " R . A . B . " that stated he had already taken it . Harry tells his friends that he does not plan to return next year , instead he plans on seeking out R . A . B . and the other Horcruxes so that he may put an end to Voldemort ; Ron and Hermione remind Harry that they are his friends and will help alongside him in his goal . Sets . Sets Released for the Movie Sets That Include Allusions To This Movie / Book