Nyssa arrives in "The Keeper of Traken" story which is essentially a horror story with The Master providing the evil guy sneaking around and killing people. Nyssa's stepmother is one of the victims, so Nyssa signs up with the doctor and Adric. She subsequently witnesses the Fourth Doctor's regeneration into the Fifth, and stays with the Doctor until the "Terminus" story when she decides to stay on board the Space Station when the TARDIS leaves in order to turn the station into a hospital. Nyssa's kisses the Doctor goodbye. Was that the doctor's first big smacker in 700 years? Come to think of it, that was the story where Nyssa took off her skirt and played the last part of the show in her underware. No wonder the doctor wanted a kiss
Sutton later described the underware show as "a present for the fans." Well, thank you very much.
Nyssa is played by Sarah Sutton, (born Dec 12, 1961 in England) . Sutton was the youngest actress to play a companion in the series. After the doctor, Sutton played some interesting roles but not a lot of them. She is married with a daughter.