Star Trek: Deep Space Nine: Season 7, Episode 20

7 - 20: The Changing Face of Evil

The Breen-Dominion Alliance launches a devasting attack at the heart of the Federation, and the Federation Alliance struggles to maintain its foothold in Cardassian space. Kai Winn, under the guidance of Dukat, begins researching forbidden texts about the Pah-wraiths. On Cardassia, Damar begins a rebellion against the Dominion.