The Magician's Apprentice/The Witch's Familiar
The opening double episode to Series Nine. Taken together, the episodes are still interesting, yet disjointed. How Clara has become important at UNIT hasn't been answered, nor has the question of why Colony Ssarf has come to serve Davros. It's clear why Davros wants him there, but what does Colony Ssarf (or the constituent snakes) get out of it? However, the addition of the second episode has cleared some things up, such as what the Doctor was up to, and the source of his shame.
And the follow up to Young Davros' encounter was well done. 7.25/10.