4. The Daleks' Master Plan (First Doctor, Season 3 - Story 21)
Nine parts from this massive 12-part story arc are missing (only part two, five and 10 still exist). A complete version of this "episode" would rank The Daleks' Master Plan
as the second-longest Doctor Who serial to date, sitting just under the four-episode, 14-part Sixth Doctor serial, The Trial of a Time Lord. The Daleks' Master Plan
marks the first time a companion has died on Doctor Who, as well as the first time actor Nicholas Courtney, who would go on to play the integral near-companion and UNIT commander, Brigadier Alistair Gordon Lethbridge-Stewart, appeared on the show. It also stars the "Meddling Monk," a pre-Master Time Lord antagonist, who ostensibly does what he does best - meddle in the Doctor's affairs. Not to mention, there are Daleks. So, you know. That's a plus.