Story 195 - The Unicorn and the Wasp

In which the TARDIS materialises in the grounds of Lady Clemency Eddison's country estate. The Doctor recognises that they are in the 1920's, and sure enough it is December 1926. He and Donna decide to gatecrash Lady Eddison's weekend party, and discover that the guest of honour is the celebrated crime writer Agatha Christie. Other guests include the local vicar, the Rev Arnold Golightly, historian Professor Peach, and a young woman named Robina Redmond. Also present are Lady Eddison's husband, Colonel Hugh Curbishley, and their son Roger. The housekeeper, Miss Chandrakala, raises the alarm when she finds the professor dead in the library - murdered with a piece of lead piping. The Doctor pretends to be a police officer, with Donna his assistant. He takes charge of the investigation, though Mrs Christie also starts to look into the crime.
The writer is troubled at this time as her marriage is failing, and the Doctor has noted that this is the date when she famously went missing for a number of days - found later in a hotel in Harrogate claiming to have lost her memory.
The Doctor and Agatha interview all of the family and guests, as well as some of the staff, in order to discover which of them had no alibi for the time of the murder. All claim to have been occupied elsewhere, though Roger lies about his whereabouts as he was off with his lover - the young footman Davenport. Others, like the Reverend and Robina, were alone in their rooms with no-one to corroborate their stories.
Donna explores the upper floors of the house and finds a locked bedroom. She forces the butler, Greeves, to open it for her. There are some children's playthings in the otherwise empty room. She is suddenly attacked by a huge wasp-like creature, which flies in through the window.

She uses her magnifying glass and the bright sunlight to chase the creature off. When the Doctor and Agatha arrive they find that it has left its sting embedded in the door. They then see the wasp in the corridor, and once again Donna brandishes the magnifying glass to chase it away. The Doctor takes a sample from the sting and identifies the creature as a Vespiform. These aliens can transform themselves into human beings - so anyone in the house might be the wasp in disguise.
The Doctor then comes under attack when someone poisons his drink. He rushes to the kitchen where he concocts a remedy which allows him to exhale the toxin from his body. Soon after, Miss Chadrakala is killed when the wasp knocks a stone statue off the roof, crushing her to death.
That evening, everyone is gathered for dinner. There had been talk through the day about a notorious jewel thief nicknamed "The Unicorn" who has been terrorising Society. Lady Eddison is known to possess a rare treasure known as the Firestone, and has been worrying that it might be a target for the thief. During a power cut, the assembled group hear the buzzing of the wasp. When the lights are restored, they discover Roger dead, knifed in the back, and the Firestone missing.

After dinner, the Doctor and Agatha assemble everyone in the drawing room. Between them they have sorted through the clues and deduced who the killer is. Other secrets come to light - such as Col. Curbishley's faking of a disability. He pretended to be wheelchair-bound as he was worried his wife might abandon him. Robina Redmond is revealed as an impostor. She is really the Unicorn. She returns the Firestone. Lady Eddison is then forced to admit that she returned from India some 40 years ago pregnant though unwed, accompanied by Miss Chandrakala. She locked herself away in the upstairs bedroom which Donna had explored until her child was born. It was a boy, and he was given up for adoption to an orphanage. The father had been a mysterious man named Christopher who was really a Vespiform who wanted to experience human life. He had drowned in a flood soon after she fell pregnant. He had given Lady Eddison the Firestone - really a Vespiform Telepathic Recorder. The Rev. Golightly had previously mentioned being raised by a religious order, and is of the right age. He had claimed to have overpowered some thieves in his church a few nights before - which the Doctor finds surprising for someone so timid. The stress of the incident in the church had combined with Lady Eddison's wearing of the Firestone as she read one her favourite novels - The Murder of Roger Ackroyd, by Agatha Christie.

Golightly had suddenly discovered his true nature, whilst the works of Miss Christie had downloaded themselves into his mind. This was why the murders looked as if they had come straight out of one of her books. Prof. Peach had been killed as he had discovered the boy's birth certificate, and Miss Chadrakala had, of course, known of his illegitimacy. He was simply jealous of Roger having usurped his place in Lady Eddison's affections.
Deciding she is somehow to blame for the deaths, Agatha takes the Firestone and drives off into the night, pursued by the Vespiform. The Doctor and Donna give chase. At a nearby lake, Donna throws the jewel into the water - recalling that Christopher had drowned. The Vespiform dives in after it. As it drowns, Agatha begins to die, as she is psychically linked to it. Its death frees her, though the experience has left her in shock. The Doctor and Donna take her in the TARDIS and leave her at the Harrogate hotel where she will later be found, her memory of recent events shrouded.
Back in the ship, the Doctor shows Donna a paperback reproduction of one of Agatha's books - Death in the Clouds. The cover shows a close-up image of a wasp - suggesting that she might have remembered something of what happened after all.

The Unicorn and the Wasp was written by Gareth Roberts, and was first broadcast on Saturday 17th May, 2008. Although not shown until half way through the run, it was one of the first stories filmed for Series 4. The director is Graeme Harper.
Ever since the series had returned in 2005, the concept of the "Celebrity Historical" had been introduced. Series 1 had seen the Doctor and Rose meet Charles Dickens, with elements of the plot mirroring some of his works. Series 2 had seen the Doctor and Rose then meet Queen Victoria. For Series 3 Gareth Roberts had written The Shakespeare Code. The dialogue for this had been liberally sprinkled with lines from the Bard's works. Roberts builds on this here with numerous references to titles of Agatha Christie works (see below). We also have a running gag where Donna forestalls some of the works she has not yet written, claiming copyright on Miss Marple and the everyone-dunnit plot to Murder on the Orient Express.
Another running theme since 2005 had been the Doctor kissing his companion - though in each case it was never a romantic gesture. Here it is done purely for laughs, as Donna has to do something which will shock the Doctor in order to make his anti-toxin work.
As well as the works of Agatha Christie, the murder mystery board game Cluedo (Clue in the US) is another inspiration. Professor Peach is killed in the library with a piece of lead piping, for instance. The game has a number of suspects, who have colour themed names, including a Professor Plum. Some of Roberts' other characters mimic these. Robina Redmond, for example, is based on Miss Scarlet, whilst the Rev Golightly is the Rev. Green. Colonel Curbishley is Colonel Mustard, and so forth. All of the murder weapons found in the game make an appearance somewhere in Roberts' story - lead pipe, revolver (Robina has one), length of rope (a curtain cord features), candlestick (on the dinner table) and knife - found lodged in Roger's back.

Choosing a giant wasp to be the story's monster derived from that book cover - a Poirot tale. The image was used on the front of the 1957 Fontana paperback. I recall seeing this very cover as a child, and initially thought that the story had giant wasps in it. Wasps also tied in with the story arc about the bees disappearing, which also gets a mention here.
Roberts stated that it was always his intention to write a very humorous episode. He was a great fan of Christie, though it was actually Producer Phil Collinson who suggested the idea of a murder mystery featuring the writer.
The guest cast is headed by Felicity Kendal, as Lady Eddison. She came to fame through the BBC self-sufficiency sitcom The Good Life, opposite Richard Briers. Playing her husband is Christopher Benjamin. He had previously been Sir Keith Gold in Inferno, but was best known as Henry Gordon Jago in The Talons of Weng-Chiang. Son Roger is Adam Rayner. Agatha Christie is played by Fenella Woolgar. She had appeared on screen several times previously with David Tennant - including the 1920's set Bright Young Things, and the period drama He Knew He Was Right.
Tom Goodman-Hill is Arnold Golightly, and Robina Redmond is Felicity Jones. Davenport is Daniel King, and Miss Chandrakala is Leena Dhingra, whilst the doomed Prof. Peach is Ian Barritt.

Overall, it is a fun episode, which plays with the conventions of the typical country house murder mystery in general, and with the works of Agatha Christie in particular. There's a drinking game in spotting the novel and short story titles.
Things you might like to know:

• There was originally going to be an opening and closing sequence featuring the Doctor and Donna visiting the elderly writer near the end of her life, with the episode as shown acting as a flashback in between. The older Agatha was played by Daphne Oxenford, who had featured as a hologram in Dragonfire. The sequences were filmed but then deleted, and the sequence with the book cover inserted later instead. You can see the deleted scenes on the Series 4 DVD / Blu-Ray box set.
• David Tennant's father, Sandy McDonald, who just happened to be visiting the filming of the lawn party scenes, was roped in to cameo as a footman.
• Despite a December setting, the story is clearly filmed on a warm summery day.
• The original conclusion to the story was to have been the Doctor ramming the Vespiform with the car he was driving. Tennant objected, as this made him look like he had murdered the creature. It was changed to Donna throwing the Firestone into the water - recalling what had happened to Christopher, and also referring to water-filled wasp traps.
• The Doctor reminisces about an adventure involving a computer kidnapping Charlemagne. This was a reference to an on-line short story called "The Lonely Computer" by Rupert Laight, which appeared on the BBC Doctor Who website in 2008.
• You might be puzzled by Davenport's startled reaction when the poisoned Doctor asks him for ginger beer. That's because "ginger beer" was employed as Cockney rhyming slang for "queer" - so the footman thinks the Doctor is outing him (even though everyone seems to act as if his relationship with Roger is common knowledge).
• The Doctor uses the phrase "buzz off" - referring to the noise a wasp makes. The phrase derives from the early days of the telephone, when they used to buzz instead of ring.
• The Doctor takes the paperback book from a storage closet which has items beginning with "C" in it. These include a Cybus Cyberman chest plate, as well as the Carrionite crystal ball (referring back to Roberts' previous story. The Doctor had previously said that he was going to store this in a TARDIS attic, but it's under the console here.
• Donna really seems to think that Noddy might be real.
• A lot of the Christie story titles were actually added by Russell T Davies. One he decided against in the end was the controversial original title for what we now know as And Then There Were None, or The Ten Little Indians. Donna was to say: "It's like Ten Little-" but the Doctor interjected with "Niggles aside, we'd better look in the library...". 
• And finally - the references that did make it to the screen:

1. Donna mentions Murder on the Orient Express, not realising Christie has yet to write that story.
2. She gives Christie the idea of an old lady who investigates crimes from her home in a small English village.
3. Two novels are seen on screen - The Murder of Roger Ackroyd, being read by Lady Eddison, and Death in the Clouds in the TARDIS closet.
4. The Professor exclaims "Why didn't they ask - Heavens!" as he is attacked. There is a Christie book called Why Didn't They Ask Evans?.
5. On finding a scrap of paper the Doctor asks "M or N?".
6. Agatha mentions Sparkling Cyanide when the Doctor is poisoned.
7. There are yellow irises on the dinner table. Yellow Iris was the short story which was later expanded to become Sparkling Cyanide.
8. Throughout, the Doctor is The Man in the Brown Suit.
9. Miss Chandrakala refers to the Professor's book as a Dead Man's Folly. 
10. Donna mentions The Body in the Library (Prof Peach's).
11. The cook says that the murder has set the Cat Amongst The Pigeons.
12. Agatha refers to the unknown killer as Nemesis, and as The Secret Adversary.
13. She tries to explain away the giant wasp as They Do It With Mirrors.
14. Lady Eddison says that Miss Chandrakala had an Appointment With Death.
15. Asking for Agatha to explain what is going on, the Colonel insists she put her Cards on the Table.
16. The house and its occupants are described as a Crooked House.
17. The Doctor states that it has been an Endless Night.
18. Christopher was said to have been Taken at the Flood.
19. A character feigning disability features in After The Funeral.
20. Going round the suspects, the Doctor mentions The Moving Finger of suspicion.
21. Agatha says that Death Comes As The End when the Vespiform dies.
22. Last, but by no means least, is the Doctor's contrived pun to sum up what has happened: "Murder at the vicar's rage..." - playing on Murder At The Vicarage.