Another choice from Series 8. This one starts as inconspicuously as possible, with the Doctor and Clara exchanging some trademark banter concerning Clara's appearance and impending date. Then, the TARDIS phone rings and the pair are transported to a mysterious room with two other mysterious characters, all of whom hear that they have agreed to a memory wipe. At first glance, this introduction feels like a gimmick. However, by the end of the episode, everything is tied together, albeit not in an entirely satisfying manner. The scene definitely makes more sense upon a rewatch. It's certainly a well-paced scene that sets up a compelling mystery for the rest of the episode to follow.
