The Doctor tries to figure out why people are disappearing at the Frost Fair on Doctor Who. "Thin Ice" is the fourth episode of the show's tenth season.
The Doctor faces off with the Time Lords in a struggle that leads them to the end of time on Doctor Who. "Hell Bent" is the 12th episode of the show's ninth season.
The Doctor: It's a risk. Graham: Oh, like none of our other trips have ever been risky. The Doctor: I have apologized for the Death Eye Turtle Army! Profusely.
