In a Harry Potter novel, Sirius Black is a convicted murderer who escapes from this island prison in the North Sea
This is because, 
unlike the movies, the books were told exclusively through the eyes of Harry 
Potter,... [DOC] [TLE] Dementor | Harry Potter Wiki | Fandom powered by Wikia [PAR] The island in the North Sea on which the wizard prison is built has never ... "mass 
murderer" Sirius Black, who had recently escaped from Azkaban in 1993.