Celia Soames

 was looking for a Vampire thinking it was Count Dracula. She spotted the Fourth Doctor over a vampire's victim and assumed he was vampire. She described herself as a professional vampire hunter. She went with the Doctor to the Labyrinth under Buda Castle. When attacked by the now vampiric Anita Kereki she stabbed her with a stake in the lower back. She wanted to become a vampire queen of Zoltán Frid and was his human agent. The Doctor told her that all she was doing was given Frid the power to kill her. She knew that Frid would kill her so between her and the Doctor they put a hypnotic suggestion which got made anyone who heard the phrase sunbathing want to walk in the sun. (AUDIO: The Labyrinth of Buda Castle)