Casimer was a time traveller from 23rd century Earth. She received a time twister for Christmas and decided to try it out. The Doctor's TARDIS was caught in its wake and landed at Sommerton Manor in 1783. The Third Doctor chased Casimer to various points in the history of the manor. Her anxiety was causing the time jumps for both of them. After calming her down, they were able to return to 1783. The Doctor returned her home and then disassembled the time twister. (PROSE: The Sommerton Fetch)