Sara Kingdom is a fictional character played by Jean Marsh in the long-running British science fiction television series Doctor Who. A security officer for Mavic Chen from the 40th century, she later joined the First Doctor and Steven to work against Chen's interests. She is sometimes classed as a companion of the First Doctor but the BBC's official Doctor Who website does not include her in their list of companions. Her status as a companion is commented upon in its Episode Guide. Sara appeared in parts four to twelve of the twelve-part 1965 serial The Daleks' Master Plan. Only two episodes in which she appears still exist in the BBC archives. Her character took on elements of the companion role to replace the character of Katarina, who was killed off earlier in the same story. Appearances Television Sara is a Space Security Agent, the sister of Bret Vyon, another agent who is aiding the Doctor in trying to defeat the Daleks. There is an implication that she was born on Mars Colony 16, where her brother had been "bred". Told that Vyon is a traitor by Mavic Chen, the Guardian of the Solar System (who was in league with the Daleks) and ordered to kill whoever is working with him, she shoots her brother and is about to do the same to the Doctor and Steven when they are transported across space to the planet Mira. There she learns, to her horror and grief, that her unquestioning obedience has not only led her to unjustly kill her brother, but also that by doing so she has prevented Vyon from warning Earth of the Dalek plot. She then joins the Doctor in his fight, briefly travelling in the TARDIS to several different locations in space and time as the Doctor and Steven try to return the ship to Kembel for a final confrontation with Mavic Chen and the Daleks. When the Doctor activates the Time Destructor—a device that accelerates time—as part of his plan to stop the Daleks, he orders his companions back to the TARDIS for their protection. However, Sara follows him, not knowing the nature of his plan but concerned it might fail. As a result, she and the Doctor are both caught in the field of the Time Destructor as it rapidly ages everything around it. While the Doctor, being a Time Lord, can withstand the worst of