Sirius Black: Enough talk,Remus! C'mon, let's kill him!
Professor Lupin: Wait!
Sirius Black: I did my waiting! Twelve years of it! In Azkaban!
Professor Lupin: Very well, kill him. But wait one more minute. Harry has the right to know why.
Harry: I know why! You betrayed my parents! You're the reason they're dead!
Professor Lupin: No, Harry, it wasn't him! Somebody did betray your parents, but it was somebody who, until quite recently, I believed to be dead.
Harry: Who was it then?
Sirius Black: Peter Pettigrew! And he's in this room, right now! Come out, come out, Peter! Come out and play!
In the Shack, the Harry, Hermione and Ron learn the truth about the death of Harry's parents.