 As of October 2013, 97 episodes are unaccounted for. The missing episodes span 26 serials, including 10 full serials. Most of the gaps are from seasons 3, 4, and 5, which currently lack a total of 79 episodes across 21 (out of 26) serials. By contrast, seasons 1, 2, and 6 are missing a total of just 18 episodes, across 5 (out of 25) serials. Of the missing stories, all but three – Marco Polo, "Mission to the Unknown", and The Massacre of St Bartholomew's Eve – have surviving clips. All episodes also have full surviving audio tracks.
