Pierre and his father René flee France for London and change their last name from Poulenc to Boulanger. Rene begins his rise in the concert world there, but after soloing with the Royal Philharmonic Orchestra (under the baton of Sir Galton), his violin is stolen. Pierre and his father work to track it down, but it's been sold. Pierre goes to steal it, but turns into a werewolf and kills a guy.
Then this happens again. But the third guy manages to cut off Pierre-wolf's hand and not be brutally murdered. When René sees that Pierre can never again play the life-sustaining violin, he breaks the violin, killing his son. Possibly René was slightly bothered by the murders his son committed also.