Mission to the Unknown serves as an introduction to the upcoming epic adventure The Dalek's Masterplan. What's so unusual about Mission to the Unknown is that for many years it was the shortest in-canon Doctor Who story (only one twenty five minute episode) and that it didn't feature The Doctor or any of his current companions.
Mission to the Unknown is no longer the shortest in-canon Doctor Who story, that record was taken away by the first Children in Need special in 2005, which takes place between the last full-length Ninth Doctor episode (The Parting of the Ways) and the first full-length Tenth Doctor episode (The Christmas Invasion). However, Mission to the Unknown still holds the record for shortest in-canon Classic Who story.
Since Mission to the Unknown is completely missing from the BBC archives, I chose to experience this story via the Target novelization. Chapters Two and Three of the Target novelization to the Dalek's Masterplan Part I-Mission to the Unknown contain the relevant novelization of the episode.
The story takes place in a jungle on Kembel. Three men from Earth have crash landed on the planet and are attempting to contact a rendevous ship. One of the men, Garvey has been stung by thorn from a Varga plant that grows on Kembel, and the poison is slowly turning him into a Varga plant.
Marc Cory, discovering that Garvey has been stung by a Varga thorn, kills Garvey and warns the third man, Lowery, to avoid being stung as well as he would have to kill him as well. Cory then reveals to Lowery that he's a member of the Space Security Service and that he is investigating reports that the Daleks have a base on Kembel. The Varga plants are native to the Dalek's homeworld, and a clue that perhaps the Daleks do have a base on Kembel.
Lowery is stung by a Varga thorn but tries to hide this fact from Cory. Meanwhile, the Daleks and their allies are holding a meeting at the Dalek base, where it is decided to approve plans for invading Earth. The Daleks destroy the Earth spaceship, and Cory kills Lowery, after discovering that he has been infected by the Varga thorn. The Daleks eventually catch up with Cory and exterminate him, but not until Cory has recorded a message about what exactly is going on here on Kembel.
Mission to the Unknown does serve as a decent prequel to the Daleks' Masterplan, but why was it sandwiched in between two unrelated stories (Galaxy 4 and The Myth-Makers)? Wouldn't it have made much more sense to air this after the Myth-Makers, just prior to airing the first episode of the Daleks' Masterplan?
Mission to the Unknown doesn't work very well as a stand-alone story, however and if one was around back in 1960s, one would have had to wait five weeks for the payoff with the first episode of the Daleks' Masterplan. Mission to the Unknown was an unusual experiment, but the fact that this was never tried again I think says a great deal about how well the idea was received by audiences.
