Dame Agatha Christie was a famous English writer best known for her murder mysteries. Her prolific body of work was in print billions of years after her death, establishing her as the best-selling author of all time. She was also known for having disappeared in 1926, being found in a hotel under an assumed name and claiming no memory of the ten days during which she had been missing.
Meeting the Doctor edit
In 1926, Agatha learned her husband had begun an extramarital affair. She nevertheless attended Lady Eddison's party as guest of honour, carrying on with her life. There, she met the Tenth Doctor and Donna Noble, who she quickly grew to trust when another guest, Professor Peach, was found murdered in the library. Agatha found a piece of paper in the library fireplace while the Doctor investigated the Professor's body for clues; he had died at 4:15 PM.
After the Doctor established himself as Chief Inspector Smith from Scotland Yard, she assisted him by having the five suspects wait in the sitting room until he finished investigating an unnoticed morphic residue. She also took issue with his enthusiasm at getting to solve a case with her, saying she would work with him "for the sake of justice, not for your amusement." Afterwards, she joined him in questioning the suspects while Donna investigated upstairs. This got them nowhere until the Doctor noted he had seen her taking the little piece of paper; it said "maiden." They were left with no clues unless Donna managed to find anything of interest in the rooms above.
Along with the Doctor, Agatha later went to Donna, who was screaming in terror at a giant wasp; Agatha misinterpreted the "giant wasp" to be a simple bee. However, the stinger the wasp had left embedded in the door changed her mind. The Doctor explained, in big words, that there were plenty of alien insects, but none lived in Earth's galactic vector. Thinking the Doctor had lost his mind, Agatha told him there was no thing as giant wasps; he agreed, but pointed out the question was why it was there.
She later went outside with them to find Ms Chandrakala had been crushed by a gargoyle and had said "the poor little child" before passing; the giant wasp had pushed the statue on her from above. Spotting the wasp, Agatha now believed something was afoot, but still didn't think the wasp was real until she came face to face with it. It fled into a corridor and resumed human form amongst the other guests. Afterwards, Agatha was visibly suffering from a crisis of confidence in her work, but Donna did her best to sit down with her and cheer her up, armed with the knowledge not only of Christie's greatness but also the fact that she'd found the Doctor again after the disaster with Lance Bennett on her wedding day. (TV: The Runaway Bride). She then immediately discovered the tool box containing the Unicorn's equipment and then also displayed her expertise in poisons (which she utilised in her works) by correctly identifying that the Doctor had been given cyanide.
After the wasp — in fact, a Vespiform — had claimed Lady Eddison's son and heir Roger as its latest victim at dinner, Agatha pointed out, when she saw that the Doctor was still grappling with what could drive a Vespiform to kill, that "the murderer is as human as you or I." The Doctor had an epiphany, saying he'd forgotten she was the expert, and disregarded her dismissing herself as a "purveyor of nonsense" and encouraged her to crack the case.
Oh, no, no, no, no. 'Cause plenty of people write detective stories, but yours are the best. Why? Why are you so good, Agatha Christie?
Because you understand. You've lived. You've fought, you've had your heart broken...you know about people. Their passions, their hope and despair and anger - all of those tiny, huge things that can turn the most ordinary person into a killer. Just think, Agatha! If anyone can solve this, it's you.
With everyone gathered, Agatha — with the Doctor's assistance in extraterrestrial matters — revealed the Unicorn was pretending to be Robina Redmond, one of the guests, and that Lady Eddison had had a child before Roger with a a Vespiform in India forty years earlier. That child was the very Reverend in that room, Arnold Golightly; his mind was overloaded with the contents of The Murder of Roger Ackroyd when the Firestone linked his mind to Lady Eddison, who was reading that book.
Enraged by being discovered, the Reverend chased after Agatha, who had taken the Firestone to lead him away lest he murder again. She led him to the lake, where she planned to drown herself and it. Luckily, Donna and the Doctor arrived, tossing the jewel into the lake, causing Golightly to go after it and drown. However, Agatha's mind was linked to him and she began to die with him until he decided to let her go.
The stress from the link made her lose her memories; the Doctor took her forward eleven days and left her outside a hotel in Harrogate, where she revived with no conscious memory of the events. Fragments of memory later emerged in her storytelling, including Donna's suggestions of her later books, as well as the Vespiform's wasp-like appearance, which inspired the cover of a book, Death in the Clouds. (TV: The Unicorn and the Wasp)
Apart from The Murder of Roger Ackroyd, Christie had written five other novels by 1926, but had not yet written Murder on the Orient Express nor her Miss Marple series. A subconscious memory of the Vespiform remained with Christie; a wasp played a role in one of her later novels, Death in the Clouds. (TV: The Unicorn and the Wasp) Centuries after its publication, a copy of Murder on the Orient Express found its way into the possession of Professor Lasky. (TV: Terror of the Vervoids)
Christie's works were still in print as late as the year 5,000,000,000, including Death in the Clouds.
The Doctor's adventures offered subconscious inspiration for Agatha Christie. Donna Noble accidentally inspired her novel Murder on the Orient Express and the character Miss Marple. The Vespiform and the Doctor also inspired Death in the Clouds. Donna herself once remarked that she should have made Christie sign a contract. (TV: The Unicorn and the Wasp)
Other information edit
Trying to remember the name of the St Agnes Abbey, Clyde Langer could only remember that he thought it was some lady writer's name or her old lady detective. He didn't remember the name until Sarah Jane Smith guessed Agatha Christie. (TV: Eye of the Gorgon)
Behind the scenes edit
Actor's view/preparation edit
In her Q&A for Doctor Who Magazine , Fenella Woolgar said she read The Murder of Roger Ackroyd and Christie's autobiography to prepare for the role. When she won the part, she was also reportedly the first casting suggestion from David Tennant to be approved.
Woolgar also said she approved of the idea of Christie being a companion of the Doctor, and when Doctor Who Magazine remarked, "Who'd've thought Agatha Christie could be sexy, eh?", she informed/reminded them that Christie had had quite a few admirers for her looks when she was younger. This would make sense — Christie was 36 at the time of her disappearance, which meant she would be the same age meeting the Doctor and Donna, and lived to be 85.
Deleted scene edit
In a scene included in the Series 4 DVD, late in her life and soon before her death, Christie, who is played by Daphne Oxenford as an elderly woman, begins to experience dreams and flashbacks of her adventure with the Doctor. Ultimately, the Doctor and Donna visit her (in what appears to be immediately before Silence in the Library), at which point her memories of the adventure began to return - and the Doctor reminds her of what happened. This scene does not present a continuity issue, as Donna is seen to be basically parroting the words the Doctor said to her regarding Agatha being the best-selling writer of all time in the original ending, allowing both to exist. The fact the Doctor has chosen to inform Agatha about the future edition of her books as well as reminding her about what happened suggest the meeting takes place soon before her death, which would place the scene in 1976.