Harry Potter and the Prisoner of Azkaban Sirius Black dementors Remus Lupin Patronus charm Shrieking Shack James Potter Peter Pettigrew Time Turner Hippogriff Harry Potter
In the third novel, Harry Potter and the Prisoner of Azkaban, Harry learns that he is targeted by Sirius Black, an escaped convict who allegedly assisted in his parents' murder. As Harry struggles with his reaction to the dementors – creatures guarding the school that feed on despair – he reaches out to Remus Lupin, a new professor who teaches him the Patronus charm. On a windy night, Ron is dragged by a black dog into the Shrieking Shack; Harry and Hermione follow. The dog is revealed to be Sirius Black. Lupin enters the shack and explains that Black was James Potter's best friend; he was framed by another friend of James', Peter Pettigrew, who hides as Ron's pet rat, Scabbers. As the full moon rises, Lupin transforms into a werewolf and bounds away; the group chase after him but are surrounded by dementors. They are saved by a mysterious figure who casts a stag Patronus. This is later revealed to be a future version of Harry, who traveled back in time with Hermione using the Time Turner. The duo help Sirius escape on a Hippogriff.
