Harry Potter and the Prisoner of Azkaban · Chapter 20
Time-Turner Rescue of Buckbeak and Sirius
Using Hermione's Time-Turner, Harry and Hermione travel back three hours to save Buckbeak from execution and rescue Sirius from the tower before the Dementors can perform the Kiss.
Outcome
Buckbeak and Sirius escape; Harry realizes he conjured the Patronus stag that saved them from the Dementors.
