Alright, i'm going to pull a Trek comparison again, but it's just for imagery!
You know in Generations when the Enterprise is caught in the gravity of Veridian III, and there's that moment when it is past the point of no return, there is no getting out of it, the ship is crashing. At that moment, Data lets out an "ohhh.... shit!"
That moment summarises this 3-parter.
Absolutely brilliant stuff, and a really solid third part. It's just absolutely breathtaking, and really makes the show. An easy 10, here.