Edith Harcourt was a teacher at Brideport Elementary School in the United States, a position she took up circa 1914 and had maintained for a long 48 years by 1962, said to have taught every generation of the school since it was built.
On 23 October, after being informed of her forced retirement after the current semester by Principle Stanley Winters, a heartbroken Edith broke down in the school toilets, when she was suddenly spoken to by a "soothing" disembodied voice belonging to a piggybacker, telling her that they would help her get the respect she truly deserved. Three days later, when Edith lost control of her class, after a fight broke out between students Tommy Dalton and Stevie, the piggybacker's returned, saying that the two children needed to be disciplined. The piggybacker used its newfound host to brainwash the entire school into being its mouthless slaves, including Ryan Sinclair, who had entered the school to investigate. The piggybacker soon took its conquest to all of Brideport, using Edith's seniority to hypnotise younger citizens. Hank Dalton, who was a member of a species immune to the piggybacker's power, tried to overpower them with his weaponised, energy-shooting spanner, only succeeding once the Thirteenth Doctor used her sonic screwdriver to amplify its energy output.
Edith was soon talked down by Abner J. Endicott, one of the few citizens immune to the piggybacker's influence due to being older. Edith forcefully severed her connection with the piggybacker, killing herself in the process, something Abner believed that she knew would happen.