Harry Potter and the Prisoner of Azkaban · Chapter 17
Shrieking Shack Confrontation
Harry, Ron, and Hermione confront Sirius Black in the Shrieking Shack; Lupin arrives and reveals Scabbers is Peter Pettigrew, the true traitor who betrayed the Potters.
Outcome
The truth about Black's innocence and Pettigrew's betrayal is revealed; Snape's arrival complicates the situation.
