"Mission to the Unknown" is the second serial of the third season of the British science fiction television series Doctor Who. Written by Terry Nation and directed by Derek Martinus, the single episode was broadcast on BBC1 on 9 October 1965. The only standalone regular episode of the show's original run, it serves as an introduction to the 12-part story The Daleks' Master Plan. It is notable for the complete absence of the regular cast and the TARDIS; it is the only serial in the show's history not to feature the Doctor at all, although William Hartnell was still credited on-screen. The story focuses on Space Security Agent Marc Cory (Edward de Souza) and his attempts to warn Earth of the Daleks' plan to take over the Solar System. After the show's second production block was granted an additional episode, outgoing story editor Dennis Spooner commissioned Terry Nation to write an extra episode as a cutaway to set up The Daleks' Master Plan. Nation wrote the episode while considering a Dalek-focused spin-off; in doing so, he realised that such a story would need a hero, and used James Bond as inspiration for Marc Cory. "Mission to the Unknown" was produced by the same team as its predecessor, Galaxy 4, in a five-week period that concluded the show's second production block; the two serials were held back to open the third season. Mervyn Pinfield was originally assigned to direct the stories, but failing health prevented him from continuing, and he was replaced by new director Derek Martinus. Pre-filming took place at Ealing Studios in June 1965, while primary production took place at the Television Centre in August. "Mission to the Unknown" received 8.3 million viewers, a drop from the previous serial. Contemporary and retrospective reviews were generally positive, with praise for the script and direction, though some viewers were confused that the following serial did not immediately continue the narrative. The videotapes of the episode were wiped by the BBC in July 1974, and it remains missing with no remaining footage. Usually alongside The Daleks' Master Plan, "Mission to the Unknown" received print and audiobook adaptations, with off-air recordings used to construct the latter. In 2019, director Andrew Ireland and students of the University of Central Lancashire recreated the episode in live-action, replicating the original production value of the 1960s; released on 9 October 2019, 54 years after the original broadcast,