Charmed - Season 3 Episode 17 -

Piper and Leo feel lack of privacy and decide to move to a rented apartment. When they tell Prue and Phoebe, the Halliwell sisters recall their troubled relationship with their grandmother Penny before they acknowledge that they were The Charmed Ones. Meanwhile an evil warlock and former cat forces the sisters to kill him nine times to leave definitely his past life as a cat and transform in a warlock forever.