Battlestar Galactica: Season 1, Episode 9

1 - 9: Tigh Me Up, Tigh Me Down

After the interrogated Cylon gave Roslin the idea that Adama might be a Cylon, Roslin becomes suspicious of him. Unexpectedly, Colonel Tigh's estranged wife Ellen turns up alive in the fleet, apparently miraculously, raising the possibility that she might be a Cylon.