Growing Up in Space And Time

When Spaceship UK breaks up, the Doctor is only able to save the life of one little girl at the cost of another companion's life - Mandy Tanner. Feeling somewhat sorry for her, the Doctor offers Mandy a place to live and stay on the TARDIS, and Doctor and Mandy get to know one other as she grows up on the ship and has a life with a strange man in a strange and very old blue box.