Susan (Carole Ann Ford) was the Doctor's granddaughter. She escaped with him from the planet Gallifrey in a stolen TARDIS. From her grandfather, she has an advanced knowledge of history and science. Her first appearance was in "An Unearthly Child". Her last appearance was in "The Dalek Invasion of Earth". In that episode, she meets David Campbell (Peter Fraser), a young freedom fighter in the 22nd century. The Doctor locks her out of the TARDIS and forces her to stay behind with David.