In this episode, the Doctor and Donna head to the past, meet Agatha Christie (during her real-life unaccounted-for week), and must solve a Clue-esque murder. It’s played for laughs and was written by Gareth Roberts who did the fairly strong “Shakespeare Code” last season but it has a few problems that I couldn’t quite get past as a viewer. That’s not to say I disliked the episode. It kept me entertained. I’ll explain as I recap:

The Doctor and Donna arrive at the estate of Lady Eddison and her husband, Colonel Hugh. They are having a fancy dinner party with their premier guest being Agatha Christie, the famous murder-mystery novelist. Using his psychic paper, the Doctor adds himself and Donna to the eclectic guest list. A newspaper lists the date as December 8, 1926. The guests busy themselves with discussion of “The Unicorn” a high-profile thief. By the way, Lady Eddison has a large gem necklace she calls “the firestone” which is just waiting to be stolen by this mystery thief.

No sooner does our duo begin to ingratiate themselves into high society than guest Professor Peach is found murdered in the library with a lead pipe (see? Like Clue) by Miss Chadrakala, head of the wait staff. Donna had really been enjoying her time faking being rich and fancy, but to me it highlighted the worst aspects of The Doctor and his companion. Sometimes they act like they’re above it all, like bad tourists. They know more so everyone else is sort of looked down upon. Donna treats the butlers pretty badly and the Doctor gets really excited about the fun of solving a mystery with Agatha Christie instead of showing some compassion for a murdered person. At least Agatha chastises him for that.

Agatha and the Doctor team up to interview the guests who are all suspects. The other guests include Roger, Lady Eddison’s son; Robina Redmond, a young lady; and Reverend Golightly. There is also assorted staff helping around the estate. Everyone tells their alibi, though we see in flashback that most of them are lying for various reasons. Roger is secretly having an affair with one of the male waitstaff and Colonel Hugh was looking at porn in his den. In the funniest bit from the show, Lady Eddison accounts for her whereabouts leading right up to meeting the Doctor and Donna and repeating what we saw only minutes ago before the Doctor can finally get her to stop. “Yes, I was there for that bit.”

The Doctor’s first clue that this mystery is up his alley is that he finds “morphic residue” at the murder scene. He is positive the murderer is actually a shape-changing alien of some sort. While the Doctor and Agatha interview the guests, Donna looks for clues around the house with Miss Chadrakala. She comes across a room that hasn’t been opened in 40 years. Lady Eddison had sequestered herself there when she was dealing with a bout of malaria. Donna enters and follows a buzzing sound to the window only to be attacked by a massive wasp. And I mean massive. Bigger than a person. The CG isn’t the best, but it’s convincing enough for me and a huge step over what Classic Who could ever pull off. Donna uses the magnifying glass she took to look for clues and focuses the sun on the wasp, scaring it off momentarily. She and Miss Chadrakala get out of the room and slam the door just as its massive stinger smashes through. The Doctor comes running to help and he and Agatha see the large stinger left as evidence.

Just then Miss Chandrakala is killed downstairs and with her dying words says, “the poor child.” The Doctor believes it has changed to human form and calls out for it to show itself, only for every guest to open their hallway door simultaneously. The Doctor intuits that the killer is using Agatha’s novels as his or her inspiration.

The Doctor then realizes his tea has been poisoned with cyanide. Being a Time Lord, this isn’t instantly fatal because he has more control over his whole body but he needs to find an antidote fast. They rush to the kitchen where he gobbles down nuts for protein as well as ginger ale and other silly ingredients, and then requires a shock, so Donna kisses him. It works and he saves himself. It is exceptionally silly but at least it’s supposed to be and seeing David Tennant dump food all over himself cracked me up.

The Doctor ends up using the same logic against his hiding foe by poisoning everyone’s dinner with pepper to act as an insecticide and get the alien to show their true form. However, before his plan can work, the lights are blown out and when they are re-lit Roger has been murdered and Lady Eddison’s necklace has been stolen.

Everyone moves to the sitting room where the Doctor uses the techniques of Agatha’s protagonists to point the finger at each guest and reveal what they’ve uncovered about each person, sometimes tricking them into revealing even more. Robina is uncovered as having forged her identity and is revealed to be the Unicorn. She stole the Firestone in the confusion. Colonel Hugh is not truly wheelchair bound and has been faking his condition to keep the younger and more wealthy Lady Eddison closer to him. He gave that up without any real prompting and the Doctor admits he didn’t really have anything to accuse him of.

Agatha and the Doctor figure out that Lady Eddison never actually had malaria. She had been in that room because she was pregnant and single, from her visit to India 40 years ago. The man who impregnated her was actually a Vespiform (wasp alien!) and gave her the Firestone necklace. Apparently the necklace kept her psychically linked to her son, who she gave up for adoption. Her son is revealed to be Reverend Golightly. One day his alien biology awakened while his mother was reading an Agatha Christie novel and he believed that was how the world actually operated. Enraged at being discovered, he turns into his wasp form.

Agatha grabs the necklace and races away into the night in her car, believing it is her fault. The Doctor and Donna pursue in another car. Agatha throws the necklace into the lake and the wasp follows it drowning. Agatha, having possessed the locket last, is psychically connected to the wasp and begins to drown, but in his final act, Golightly releases her and she passes out with amnesia. The Doctor drops her off at the Harrogate Hotel where she was found, claiming not to recollect the last ten days.

In a coda, the Doctor and Donna are in the TARDIS where the Doctor shows Donna a copy of an Agatha Christie novel with a copyright date of 5 billion. The Doctor says she’s the most popular novelist of all time and one of her novels features a wasp on the cover, suggesting her amnesia had not been complete.

This episode was really close to working. Really close. In my mind, it didn’t quite pull the elements together. The sci-fi logic was very confusing. The Doctor and Donna seemed above it all instead of involved and caring.

I have to give this one two and a half out of five sonic screwdrivers. Thank goodness next week is a Steven Moffat episode.