User:SOTO/Forum Archive/The Reference Desk/@comment-24354550-20131229194352/@comment-1398253-20131230005425

User:SOTO/Forum Archive/The Reference Desk/@comment-24354550-20131229194352/@comment-1398253-20131230005425 Sounds like Tardis has Let's Kill Hitler down as the second part of a two-parter (part 1 being A Good Man Goes to War), whereas Wikipedia counts it as a unrelated episode. The two episodes both relate to the origins of River Song.