When D'Anna threatens to kill the colonial hostages unless the 4 Cylons in the fleet reveal themselves and come to her. Roslin, Lee and Bill Adama decide to front a rescue and destroy mission. However Tigh isn't having any of it and reveals he is a Cylon.
The quote at the beginning of the episode from Starbuck to Lee about for a child to reach it's true potential it's parents must die made me think for a second that the dieing leader may in fact be Adama. This could be an interesting take on the prophecies but if Adama does die I feel it may be from the heartbreak of the death of Laura Roslin more than anything else.
Bill Adama's breakdown at being told straight that his oldest friend was in fact a Cylon was without doubt a major highlight of a very good episode. If I found out my friend had been keeping something as major as this from me I would be angry and confused. Who wouldn't be - it's a powerful moment for a character who has been through a lot of emotion in the past few episodes. In particular his devotion and love for Laura Roslin.
D'Anna's return last week comes to fruition here. Her leadership is aggressive and up till now this season we haven't really seen a Cylons against Colonials episode. There has been more concern over the Cylon civil war which is bound to come back in the second half of the season. I enjoyed having this conflict back and genuinely felt Lee may actually toss Tigh and the others (mainly only Tigh) out the airlock. Some true jeopardy there between the two sides. In the end Baltar as the man of reason shows how far he has come and Roslin knowing he is the one to do so makes perfect sense.
Lastly is the revelation that Earth is finally found. Why the 4 Cylons were needed was very much a plot device, they were more of a pointer to the Angel of Death that is Kara Thrace to realise that her squeaky clean viper had the answer. I'd guessed already that this may be the case as had I correctly guessed the state that they would find Earth in, it was just a relief to see it. It's not the fact that the earth was found in a state of post Nuclear fallout but that they have found it so soon that is the exiting and yet worrying at the same time. The other mysteries including the last unknown Cylon, why are the final five different, what purpose do they really serve and how does the Opera house fit into everything have yet to be solved, also the reappearance in Razor of the original Cylon models raises hope that we will see them again. All these are bound to come to the fore in the last lot of episodes it's just a shame we have to wait so long for them.