Overview
"Revelations" is the tenth episode in the fourth season of the reimagined Battlestar Galactica. It first aired on television in the United States on June 13, 2008. The episode serves as the mid-season finale of the fourth season, with the concluding episodes of the series airing after a hiatus. The survivor count shown in the title sequence is 39,665.
Plot
The Cylons, led by D'Anna Biers (Lucy Lawless), decide to take Laura Roslin (Mary McDonnell) and the Colonial soldiers aboard the Basestar hostage to bargain for the secretive "Final Five" Cylons currently on the Battlestar Galactica. Before the departure of Admiral William Adama (Edward James Olmos) from the Basestar, President Roslin secretly orders him to attack and destroy the Basestar in the event that negotiations between the Cylons and Humans go poorly, for if they have the five they'll have Earth and he can't allow that eventuality. D'Anna asks initially that the four can leave at their own will, but after Tory Foster (Rekha Sharma) joins them (at first only under the guise that Laura needs her medication and she being her assistant, is obliged to do so). When the other Cylons refuse to disclose themselves and voluntarily go with her, D'Anna reneges and starts to order the execution of her hostages until "her people come home". Adama subsequently passes along Roslin's order to his son and acting President Lee Adama (Jamie Bamber), who reluctantly agrees.
After Tory's defection, Colonel Saul Tigh (Michael Hogan) admits to his friend and commanding officer that he too is a Cylon in order to prevent what he sees as useless slaughter. Tigh even offers himself up to be airlocked as a bargaining chip. Horrified, Adama orders Tigh to be arrested. As Tigh is escorted away, Adama tears apart his office in a fit of rage and despair. Lee uses Tigh's life, as well as those of fellow Cylons Samuel Anders (Michael Trucco) and Galen Tyrol (Aaron Douglas), as leverage, but D'Anna refuses, at one point arming the Basestar's nuclear weapons. Gaius Baltar (James Callis), also a hostage, tries to reason with D'Anna.
At Anders and Tyrol's request (who were drawn back to Kara's viper), Kara "Starbuck" Thrace re-inspects the Viper fighter she was piloting in the third-season finale "Crossroads", and discovers a hidden signal being received by the fighter (the same signal that activated the five previously).
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