Battlestar Galactica — Episode 6: Litmus

You are watching the episode Litmus When a new copy of Doral, a Cylon who had been previously exposed while serving as the Galactica's public-relations officer, sneaks aboard and blows himself up, killing three people, Commander Adama and President Roslin must finally make public the terrifying secret known only to a select few: Cylons now look like humans.