The large black dog attacks Ron, then drags him into a tunnel under the Whomping Willow. Crookshanks, appearing to be in league with the dog, Harry, and Hermione follows them through the tunnel and to the Shrieking Shack, a haunted house in Hogsmeade. They discover that the dog is Black in animal form. Lupin enters and explains that, although he believed Black to have betrayed the Potters, he realises now that it was Peter Pettigrew. Lupin admits he is a werewolf and that, while at school, the Marauders (Lupin, Black, Pettigrew, and Harry's father, James Potter) learned to transform into animals to tame Lupin during his transformations. Lupin explains that Scabbers is Pettigrew in his animal form. Pettigrew faked his death, framing Black for the murders, and hiding from Black since his escape.