Doctor Who: The Time Warrior (1973)

Journalist Sarah Jane Smith is impersonating her aunt, virologist Lavinia Smith, in order to gain access to a research centre where top scientists are being held in protective custody while UNIT investigates the disappearance of a number of their colleagues. The missing scientists have been kidnapped by a Sontaran, Linx, and taken back to medieval England, where they are working under hypnosis to repair his crashed spaceship.