Back at Hogwarts Harry has his next private lesson with Dumbledore, where he gets to know two more memories. One belongs to Morfin Gaunt, who has been visited by the young Voldemort, because he wants to know everything about his family. The memory is very short due to Morfin′s lack of recollection. On the same day Gaunt was visited by Riddle junior, the whole Riddle family gets killed. Morfin′s memory has been changed, so that he thinks he has killed the Riddle family.
The second memory belongs to Horace Slughorn. He has been asked by Tom Riddle what he knows about Horcruxes. But shortly after the question the memory starts to be foggy. This fog is caused by the self-manipulation of the memory by Slughorn. Dumbledore gives Harry the order to get the true memory of the conversation between Slughorn and Tom Riddle.
