Harry Potter and the Half-Blood Prince
Chapter 20 - Lord Voldemort′s Request
Harry and Ron are allowed to leave the hospital wing and Harry has another meeting with Dumbledore. Dumbledore is very disappointed when he hears that Harry still hasn′t been able to get Slughorn′s memory. Hereupon Dumbledore tells Harry about Voldemort′s life after school and about his wish to be the teacher for the subject Defence Against the Dark Arts. They watch another memory. This time it is a memory of the house-elf Hokey, which has been the elf of a descendant of Helga Hufflepuff.
In the memory Hepzibah Smith shows the young Voldemort that she possesses the cup of Helga Hufflepuff and Slytherin′s locket. She is poisoned shortly afterwards and both items vanish. In Dumbledore′s opinion Voldemort stole them, but the house-elf Hokey was blamed for the murder.
In the second memory Harry is able to see how Voldemort applied for the job as a teacher for Defence Against the Dark Arts. Dumbledore rejected the application and Voldemort left the school in a rage.
After seeing this memory Harry hears that the job has been cursed since then and no teacher for Defence Against the Dark Arts has stayed longer than one year. Dumbledore tells Harry that they won′t meet again unless he is able to get the memory from Slughorn.