When a ghost appeared in Grimmauld place in the summer of 1998, Harry was left with many questions. But there was one question above others. When a new student started Hogwarts in seventh year in 1977, many had questions. Sirius Black more than anyone else. And he was decided to get answers. Who was Cassiope Elezy ? What was she hiding ? Sirius Black/OC , canon compliant story