7. The Massacre Of St. Bartholomew's Eve - 4/4 Episodes Missing
A fairly unique story as it doesn't feature the Doctor for the most part. Instead the action focuses on the companion Steven, as played by Peter Purves. He becomes embroiled in the political and religious intrigues that lead to the titular massacre. A purely historical story the just focuses on exciting events of the time, with no aliens or invasions to get in the way, it could be argued that this is one of Doctor Who's earliest attempt at a political thriller. It is said that the massacre itself is depicted through a series of pictures, however until it is found (if ever) we'll never really know how effective this was. The final few minutes of this story also introduces a new companion: Dodo. Recovery of this serial would allow us to witness the Doctor meeting a woman who reminds him of his granddaughter, Susan.