"Mission to the Unknown" is a single-episode Doctor Who story. It is notable as the only such installment in the original run of the series, and also for not featuring any of the regular characters, including the Doctor, although William Hartnell is still credited on-screen.
The story concerns three men struggling to repair their crashed spaceship in a hostile jungle on the planet Kembel. It serves as a prelude to the later serial, The Daleks' Master Plan.