C is for... Christie, Agatha

The celebrated crime novelist, whom the Doctor and Donna encountered at a house party hosted by Lady Eddison, in December 1926. This was near the beginning of her literary career, and she had so far created the character of Belgian sleuth Hercule Poirot. She had just learned that her husband was having an affair. The Doctor noted the date, as this was the weekend when Christie had famously gone missing - turning up at a hotel in Harrogate a week later. A number of killings began at the house, all of which seemed like something out of one of her novels. Agatha and the Doctor began to investigate the murders. It transpired that Lady Eddison, when a young woman living in India, had met a man who was really an alien Vespiform - a wasp-like creature capable of altering its appearance - and had become pregnant by him. The child - a boy - had been sent to an orphanage. Lady Eddison had a memento of this liaison - a jewel known as the Firestone. The Doctor discovered that this had picked up Lady Eddison's thoughts whilst reading one of Agatha's books and transmitted these to her son - who was present at the gathering in the form of the local vicar, Mr Golightly. Whenever he became agitated, he transformed into a wasp form and killed those who stood between him and his mother. Feeling responsible for the killings, Agatha took the Firestone and drove off into the night, to lure the Vespiform away from the house. By the Silent Pool lake, Donna threw the jewel into the water, knowing that wasps can be drowned. However, it was still mentally linked to Agatha and she collapsed. As it died, the alien released her.
The Doctor and Donna took her to the hotel in Harrogate, her memory of these recent events blotted out. However, back in the TARDIS, the Doctor showed Donna one of her books, which featured a large wasp on the cover - suggesting that some trace of memory had remained.

Played by: Fenella Woolgar. Appearances: The Unicorn and the Wasp (2008).

• Christie (1890 - 1976) went missing around the 3rd December 1926 after a row with her husband over his affair. She was found on 14th December at the hotel, having used the surname of her husband's lover on the hotel register. The disappearance was front page news. Many assumed it all to be a publicity gimmick, or even that she trying to get her husband arrested on suspicion for her murder. The incident wasn't referred to in her autobiography.
• Donna inadvertently gives her the idea for Murder on the Orient Express, and for the spinster sleuth Miss Marple, not realising that she hasn't written these yet.
• Being a Gareth Roberts script, the dialogue is packed full of references to her story titles.