Season 4, Episode 10:
On the rebel Basestar, the Cylons, Bill, Roslin and the recently-awoken D'anna discuss what happens when they return to the fleet. D'anna refuses to give any answers about the Final Five, claiming that the Galactica crew will kill them if they find out. Roslin says they have no reason to do that because the Final Five are supposed to lead them to Earth.
However, D'anna shocks everyone by taking the humans on the Basestar hostage until the Final Four are delivered to the Basestar. A Mexican Standoff ensues between the Cylons and Colonials, which is only defused when Bill and Roslin tell the pilots to stand down. D'anna asks Bill to ferry her back to Galactica in the Raptor, which the latter refuses to do until Roslin tells him to and whispers that the Cylons can't get the four because they'll find Earth first.
Bill and D'anna return to Galactica, and Tigh, Tory, Anders and Tyrol witness her disembark. D'anna says that the Four will come to her anyway, and asks Bill not to interfere with fleet traffic so they can leave on their own. Despite Tigh's objections, Tory asks to go with D'anna under the guise of bringing Roslin her cancer medicine and they leave together.
Afterwards, the command crew draw up a plan to rescue the hostages but find themselves at a standstill because of the projected casualties. On the Basestar, Tory arrives and brings Roslin her medicine, then reveals she is a Cylon. A shocked Roslin asks Tory to release the hostages, but the latter says that she doesn't take orders from the President anymore before leaving.
As the strike team works on their plan, a hostage is ejected from the Basestar's airlock and D'anna radios them to say that she will start executing hostages every 15 minutes until the Final Four are delivered to the Basestar. She hangs up before Bill can respond, and he orders the rescue mission to go ahead as planned. He also tells the strike teams to destroy the Basestar if the mission fails.
In the hangar bay, Tigh, Anders and Tyrol all begin to hear the strange music again, and comment that something has changed with it.
Tigh goes to Bill's office and, in an effort to stop the mission and bloodshed that will follow, reveals to the latter that he is a Cylon. Bill refuses to believe his friend's identity, but Tigh says he wanted to kill himself when he found out, and wants to use himself as a hostage to force D'anna to back down.
Bill suffers a breakdown as a result of Tigh's confession, smashing his office until Lee tells him he will do what has to be done. Tigh is escorted through the ship to the launch tube and interrogated by Lee, who asks who the rest of the Final Five are. Tigh refuses to answer, while Bill calls D'anna and threatens to kill Tigh if any other hostages are killed.
Tensions escalate as Tigh confesses Anders's and Tyrol's Cylon identities, and they are arrested on the hangar deck. As he's being dragged away, Anders tells Kara that something has changed with her Viper.
Anders and Tyrol are led to the launch tube and D'anna is called again, this time with another threat by Bill that they will execute the three Cylons. D'anna still refuses to back down, while Kara checks her Viper's systems and discovers a strange signal.
The situation culminates in D'anna threatening to destroy the civilian fleet with nuclear warheads and Bill ready to vent Tigh into space before Kara stops him. She says that the Cylons have revealed the location of Earth, while on the Basestar, Baltar convinces D'anna that they can put aside their differences and work together because violence isn't the answer.
The two groups meet on Galactica and gather around Kara, who explains that she has found an unexplained signal from Earth. She suggests that it is a sign that God wants them to find the planet together with the Cylons. D'anna agrees to let the hostages go, Bill releases Anders, Tyrol and Tigh, and both sides back down.
An overjoyed Bill and Roslin discuss what they'll do when they find the planet, and says the Colonials and Cylons should land together. The fleet jumps to the source of the signal and finally discovers Earth.
Bill delivers a speech to the fleet, announcing their arrival and praising them for their resolve over the last two years. Soon after, a contingent of ships from Galactica and the Basestar travel down to the planet.
What they find isn't what they hoped for. Bill lifts up a clump of soil as it is revealed that the surrounding landscape is bombed-out and irradiated. Galactica's command crew, and the rebel Cylons, stand amid the ruins unsure of what to do
- Actually Pretty Funny: While everyone else is sporting a sad or disbelieving look when confronted with the ruins of Earth, Tyrol is smirking.
- Big Applesauce: The ruins of the first Earth.
- The Bus Came Back: Peter Laird has taken over Tyrol's job as deck chief, after last being seen in "Resurrection Ship, Part 1" (chronologically that is, the character also appeared in "Razor" but his scenes were set earlier in the timeline).
- Call-Back: The emergency beacon signal's rhythm matches "All Along The Watchtower", which the Tigh, Anders, Tory and Tyrol all heard in the Ionian Nebula.
- Continuity Nod: When Tigh reveals that he's a Cylon, Adama states that it's impossible because the first time he met Tigh, the latter had hair.
- Deus ex Machina: The hostage situation is only broken by an unexplained signal transmitting, which leads the rebels and the fleet to Earth.
- Dramatic Irony: The fleet's jubilation at finding Earth quickly turns into a Despair Event Horizon once it's revealed that it's a nuclear wasteland.
- Drowning My Sorrows:
- Gaeta begins drinking as a way to numb the pain from his amputated leg.
- Bill begins drinking heavily (leading to him smashing a mirror) after Tigh reveals his own Cylon nature to him.
- Gut Feeling: Discussed. Bill knows that the Cylons and Colonials have to go down to Earth together, rationalizing that "sometimes you have to roll a hard six".
- Heroic BSoD: Bill, as a result of Tigh's confession that he is a Cylon.
- Hostage Situation: Between the rebel basestar and Galactica.
- Internal Reveal: The rest of the cast finally learn that Tigh, Tyrol, Anders and Foster are four of the Final Five.
- Just in Time: Kara running to the hangar bay to stop Bill from venting Tigh into space as a negotiation tactic.
- Last Of Her Kind: As a result of the Hub's destruction, D'anna is the only one left of her model.
- Manly Tears: Bill does not take Tigh's confession that he's a Cylon well at all.
- Mexican Standoff: The bad blood between the humans and rebel Cylons has them do this twice before the tension is defused.
- My God, What Have I Done?: In his sorrow after learning that Tigh is a Cylon, Bill tells Lee that it's his fault for giving the fleet false hope.
- The Promised Land: Earth. It turns out to be cruelly subverted when the fleet discovers that it is a burnt-out wasteland.
- Reaction Shot: A long variant of this during the final shot of the crew, who have landed on Earth.
- The Reveal: The surface of Earth, which is a burnt-out wasteland.
- Thrown Out the Airlock: Played straight and averted. A hostage is executed in this fashion by Biers, and Tigh is almost executed in the same way until the Cylons back down.
- Strategy Schmategy: Realising the alliance with the Cylons could break down at any time, Bill choses to jump the entire fleet straight to Earth rather than do a reconnaissance first.
- Wham Episode: The discovery of Earth isn't as momentous as the Galactica crew thought it would be.