Mavis is a privately-owned diesel shunter who works for the Ffarquhar Quarry Company, based at Ffarquhar Quarry. In the television series, she also works at the Sodor Slate Quarry.
Lance Sterling (Gordon), a secret agent, finds himself transformed into a pigeon. He then sets out with his associate Walter (Thomas) to stop a villain who is using Sterling's disguise to carry out a dangerous plan.
