The one where Doctor Who meets Carmen Sandiego.
The Doctor and Romana II go on a holiday in Paris, and soon find themselves accidentally investigating a fracture in time. They meet up with a very confused detective named Duggan, whose job up until now had mostly involved divorce cases, and who plans on solving the mystery of the day by punching things. While the Doctor and Romana merrily confuse him even more, they all get captured by a local rich guy named Count Scarlioni.
Scarlioni turns out to be an alien who's having a bit of trouble with his space ship. He also owns six copies of the Mona Lisa. All of which appear to be authentic. Oh, and the original is still hanging in the Louvre. Fed up with having to cater to Scarlioni's zany schemes, the Doctor just walks back to his TARDIS, vworps over to Italy and plans to ask Leonardo da Vinci himself what's going on. But his old friend isn't at home, and instead, another version of Count Scarlioni greets the Doctor in Leonardo's house.
The six Mona Lisas (Monas Lisa? Monae Lisae?) are all Count Scarlioni's legit property, who (as if all the Monas weren't enough) has a scanner for alien life, cleverly disguised as a bracelet on his wife's wrist. The wife, however, isn't aware that her husband is an alien, and gets the shock of her life when he takes off his mask and reveals a face full of writhing green tentacles. He's actually Scaroth, last of the warlike Jagaroth. As it turns out, when his spaceship exploded at the dawn of Earth time, his consciousness was scattered throughout history. His plan revolves around reuniting all of his selves.
All six paintings are original Mona Lisas, all painted by Leonardo da Vinci in the sixteenth century. Scarlioni intends to steal the one in the Louvre and then carefully sell each of the Monae to a different private collection. The proceeds will fund Scarlioni's time travel to prevent the crash from ever occurring. Romana, carrying the Idiot Ball of the day, helps him out a bit.
The Doctor doesn't especially mind all that... until he discovers that the crash of Scarlioni's spaceship was the "spark" that kicked off the development of life on Earth. Now they must work out how to defeat a being who's had four hundred million years to plan his escape. Eventually, Duggan solves the whole thing by just punching Scarlioni really hard in the face. Humanity saved!
As if all that weren't enough, John Cleese and Eleanor Bron have cameos.
This episode was the first one filmed outside of Britain and Tom Baker has commented that it was a bit startling to do shooting without the crew having to hold back throngs of fans, since Doctor Who had never been shown in France at this point.
It was never adapted in the Target Doctor Who Novelisations range because Douglas "I love the sound of deadlines swooshing by" Adams, notorious procrastinator, never got around to it. It finally got one in May 2015.
- Absentee Actor: Or rather, absent character. K9 was removed from the scripts, as there was no way the prop would function on location in Paris.
- Affably Evil: The Countess Scarlioni. Count Scarlioni projects this, but it's just a facade
- Alien Arts Are Appreciated: The Doctor himself seems to appreciate human art. On the other hand, Romana didn't seem as impressed when they visited the Louvre.
- Aluminum Christmas Trees: There actually was a plot to steal the Mona Lisa and sell several other forgeries off as real; of course, given the fact that it happened in 1911, it had already become a mere trivia point by the time "City of Death" was conceived, despite the theft helping the Mona Lisa become the most famous work of art in the world.
- Ancient Astronauts: Scaroth.
- Artistic License – History: 400 million years ago was the Devonian period, also known as the "age of fish". For the beginning of life, 4 billion years ago would be a better fit.
- To be precise, the landscape would probably be covered by forests of moss and primitive ferns that would probably be quite thick without major herbivores. The first proper trees had yet to evolve, though.
- Battle Butler: Hermann. "What a wonderful butler, he's so violent!"
- Been There, Shaped History: The Doctor ensures that the "spark" that kicked off the development of life takes place.
- The Big Guy: Duggan fulfills this role while teaming up with the Doctor and Romana.
- Bigger on the Inside: When Scarlioni removes his mask to reveal his true alien form, Scaroth's head is bigger than the mask (having, in real life, been a mask over Julian Glover's head). Characters are shocked to find he's an alien, but none seem to notice the size difference, meaning they Failed a Spot Check. (Though years later, "Aliens of London" would establish some Applied Phlebotinum that addressed this exact problem, so don't worry about it too much.)
- Book Safe: The Scarlionis' secret collection of priceless historical books and manuscripts includes a book that's hollowed out as a hiding place for some Egyptian papyri.
- Busman's Holiday: The Doctor and Romana take a holiday in Paris and get caught up in the plot.
- The Cameo: John Cleese and Eleanor Bron as art critics. They were both filming at the BBC and Cleese knew Douglas Adams.
- Captain Obvious: Duggan: "THAT is a spaceship!" (To be fair, it's a very unusual-looking spaceship).
- Catholic Schoolgirls Rule: Romana wearing a very St. Trinian's style uniform. Lalla Ward, judging by interviews and the production notes, came up with the idea and had no concept it was a fetish.
- Chekhov's Skill: Mainly mocked and taken the piss out of, but also played straight. Duggan's tendency to randomly punch people comes round useful as he knocks Scarlioni out one last time, landing "the most important punch in history".
- Cliffhanger: The first part seems like it's going to be a basic, run-of-the-mill art heist. Then Count Scarlioni removes his face to reveal something else underneath.
- Clucking Funny: The principle of Scaroth's time altering machine makes use of a chicken regressing into an egg and back again, making light of the "chicken or the egg" question."It's the Jagaroth that need all the chickens, then?"
- Clueless Detective: Duggan claims to get results, but he's all at sea when meet him here. To be fair, when he's faced with time-travelling aliens and six genuine Mona Lisas, he can legitimately claim to be out of his depth.
- Cold-Blooded Torture: More like Cold Handed Torture. Tancredi orders the Doctor tortured using thumbscrews. However, the Doctor relents before the torturer can even begin, because the guy has cold hands.
- Comically Missing the Point: Professor Kerensky, faced with the revelation that his research, which he thought was about providing expanded food supplies to famine-stricken countries, is being funded by the alien Jagaroth for their own ends, asks, "It's the Jagaroth that need all the chickens?"
- Computer Equals Tapedrive: Among the equipment in Kerensky's laboratory.
- Continuity Nod: The Doctor uses his sonic screwdriver, which he notes he last used against the Daleks on Skaro.
- Cool Guns: Everyone from Duggan to Hermann and the Count's Mooks use Walther P38 handguns. The Countess also has a nifty little pearl-handled revolver.
- Creator Cameo: Douglas Adams and Michael Hayes make cameo appearances in the story; Adams is seen as a man having a drink in a bar, while Hayes is the shifty-looking man wearing a cloth cap and carrying a metal case who exits the train at Boissière Metro Station after the Doctor and Romana.
- Cryptic Background Reference: A throwaway line by Romana about the "Braxiatel Collection" became massive Canon Fodder in the Doctor Who – Expanded Universe, and Braxiatel himself stars in a handful of spinoff series nowadays. According to the Expanded Universe (including Big Finish), he's the Doctor's brother.
- Deadpan Snarker: Romana's running commentary on Duggan's tendency to punch people and smash stuff.Duggan: You can't make an omelette without breaking some eggs.Romana: If you wanted an omelette, I'd expect to find a pile of broken crockery, a cooker in flames, and an unconscious chef.
- Emerging from the Shadows: Captain Tancredi's entrance.
- Exposition of Immortality: The Doctor comes across several copies of the Mona Lisa which are all genuine. He travels back in time to Leonardo da Vinci's workshop and encounters the Count Tancredi, whom he's already met in contemporary Paris as Count Scarloni, and who looks exactly the same. Scarloni is revealed to be a 400 million-year-old alien.
- Expy Duggan was conceived as a parody of Bulldog Drummond.
- Faux Affably Evil: Count Scarlioni, with his exquisite manners, his refined taste, his debonair wit, his plan to undo 400 million years of history and wipe out the human race...
- For Science!: What Kerensky thinks is the reason for his research.
- Genre Savvy: Props to the Scarlionis for being pretty much the only baddies in the history of the show for seeing straight through the Doctor's Obfuscating Stupidity.
- Good Old Fisticuffs: Duggan's favourite way of dealing with anything. And the existence of life on Earth owes itself to his fists.
- Good Smoking, Evil Smoking: The Countess and her cigarette holder.
- Hardboiled Detective: Parodied; Duggan wants to be this, but aside from punching people he's clearly not very good at it.
- Heel–Face Door-Slam: Just after the Countess figures out the truth behind her husband he kills her.
- Improvised Weapon: Several times while captive at the chateau, Duggan uses whatever object is handy as a weapon, from an oil lamp to a Priceless Ming Vase. This results in the Doctor complaining about his reckless treatment of valuable antiques.
- Insult Backfire: Scarlioni takes being called "inhuman" as a compliment.
- It's All About Me: Scarloni only cares about putting himself back together-the fact that doing so would result in all life on Earth being RetGone doesn't bother him one bit.
- Just Between You and Me: Averted early on ("Can I ask you where you got these?" "No." "Or how you knew they were here?" "No." "I like concise answers." "Good."), but played straight later, when Captain Tancredi does a full-on "Since I'm about to kill you, I may as well tell you my entire plan first".
- Large Ham: Kerensky.
- Last of His Kind: Scaroth's entire plan is to stop being this.
- Latex Perfection: Scarlioni.
- The book reveals the masks were made from auton plastic.
- Liquid Assets: Dr. Kerensky is aged to death.
- Mad Scientist: Averted somewhat with Kerensky, as he doesn't realize what he's doing is destructive. Otherwise, he fits this trope beautifully.
- Man of Wealth and Taste / Badass in a Nice Suit: For '70s clothes, Scarlioni's suit is seriously badass.
- Minor Crime Reveals Major Plot: Trying to steal a painting —> Trying to erase the entire history of life on Earth.
- Mistaken for Exhibit: John Cleese and Eleanor Bron cameo as art appreciators who mistake the TARDIS for a sculpture — understandably, as it's sitting in an art gallery. They're particularly impressed when the Fourth Doctor and Romana run inside, and it dematerializes.Female Art Critic: ... Exquisite.
[Male Art Critic nods sagely]
- Nerves of Steel: Romana's reaction at seeing Scaroth horrifically murder his scientist to illustrate his threats to force her to cooperate? Smile and agree, while working out how to subtly sabotage his scheme as best she can. While having just faced up against the Daleks shows she's a quick learner in such dangerous situations, the trope just below has more of The Doctor's reaction...
- Nice Hat: Romana's.
- Nice Job Breaking It, Hero!: Nice job fixing up Scaroth's time machine, Romana.
- Noodle Incident: The Doctor's already quite familiar with Leonardo da Vinci when he goes back in time to meet him.
- Not-So-Badass Longcoat: Duggan is quite badass in himself, but his trench coat does nothing to suggest it.
- Obfuscating Stupidity: The Doctor, but the Scarlionis see right through it.Countess Scarlioni: I don't think he's as stupid as he seems.Count Scarlioni: My dear, no one could be as stupid as he seems.
- She even tells the Doctor the more stupid he tries to seem, the less she believes he is.
- Omnicidal Maniac: Scaroth knows full well the consequences of his plan of trying to stop his ship from exploding, as in it would prevent all indigenous life on Earth from ever existing, and he couldn't care less.
- One Character, Multiple Lives: Scaroth is living multiple lives throughout Earth's history simultaneously and using his shared knowledge of these lives to further his plans.
- Priceless Ming Vase: One of the many things Duggan breaks — in this case over the Countess's head.
- Punch-Clock Villain: Captain Tancredi's soldier. "I'm paid to fight," he insists casually. He isn't particularly menacing and bears the Doctor no ill will despite being prepared to torture him on Tancredi's orders.
- Rapid Aging: Used by Scaroth to kill Professor Kerensky by aging him to death.
- Reality Is Unrealistic: The real Mona Lisa is a good deal smaller than people assume, certainly smaller than it's portrayed here. Ah well, at least they didn't roll it up...
- Real Life Writes the Plot: Probably inspired by an unconfirmed theory that the theft of the Mona Lisa in 1911 resulted in the conspirators selling six copies to American collectors, each convinced they had the real one.
- RetGone: What would have happened to all life on earth had Scaroth's plan succeeded.
- Reverse the Polarity: What the Doctor does to Kerensky's equipment to demonstrate that it can move backwards through time as well as forwards.
- Scenery Porn: Ahhh, Paris...
- Series Continuity Error: Romana states her age as 125, when in her first appearance, she was 140. Though, she could be lying.
- Shut Up, Kirk!:Doctor: Count, do you realize what would happen if you try to go back to a time before history began?Scarlioni: Yes, yes I do. And I don't care one jot.
- Spheroid Dropship: The main body of the Jagaroth ship is almost perfectly spherical, although its legs mean it also has shades of Tripod Terror.
- Stable Time Loop: Life on earth would never have begun had the Doctor, Romana, and Duggan not been present back then to stop Scaroth.
- Alternatively, there was an original timeline in which Scaroth's ship exploded creating life on earth; and an altered timeline where Future Scaroth tried to stop the explosion, but the Doctor, Romana and Duggan prevented his interference, resulting in a very Close-Enough Timeline.
- Stealth Pun: In French, "City of Death" is "Cité de la Mort", which sounds almost exactly like "Cité de l'Amour" (City of Love, a nickname for Paris). Oooh la la!
- Not to mention that the title is a translation of the Greek-based word necropolis. And what is the famous necropolis found in Paris? The Catacombs of Paris, located under the city itself.
- Super Senses: The Doctor can identify Leonardo's brush-work ("It's as characteristic as a signature") and pigments with little more than a glance.
- Super-Speed Reading: "Not bad. Bit boring in the middle."
- Surprisingly Happy Ending: In the end, almost all the copies of the Mona Lisa were destroyed, except for one that the Doctor wrote on the board in felt tip marker, "THIS IS A FAKE." Unlike Duggan, that doesn't bother the Doctor in the least since a copy of a painting by the original artist is not a fake, and anyone who would want to bother x-raying the painting to find his writing to determine its monetary value doesn't appreciate the real value of art anyway.
- Trojan Prisoner: The Doctor and Romana allow Count Scarlioni to take them and Duggan prisoner (much to Duggan's chagrin), so the Doctor can learn more about Scarlioni's plan.
- Unusually Uninteresting Sight: Those people in the café seem extremely unconcerned with the multiple armed holdups that occur during the serial.
- Why We Can't Have Nice Things:
"Duggan, what are you doing? Put it down! For heaven's sake, that's a Louis Quinze!"
- The Doctor writes THIS IS A FAKE on the back of the Mona Lisa with a felt pen.
- Subverted when Duggan is about to smash a chair over Hermann's head.
- Wicked Cultured: Scarlioni.
- Would Hit a Girl: Duggan knocks out Countess Scarlioni with a vase. Justified, as she was pointing a gun at him. The Doctor is more concerned about the vase.
- Visual Pun: Duggan's method of attacking Count Scarlioni at one point.Scarlioni: Could you throw any light on this?Duggan: I can!Duggan throws the lantern he is holding at the Count, knocking the gun out of his hand.
- The X of Y
- You Have Failed Me: Sort of. Two of Count Scarlioni's henchmen have actually successfully recovered his wife's bracelet which the Doctor stole. "Good," he tells them. "But not good enough." He then has them killed and replaced with two different guys. Considering they got the bracelet, it's anyone's guess as to why he thinks they underperformed. It certainly can't be punishment for not being discreet, considering their replacements are just as brazen.
- You Have Outlived Your Usefulness:
- Bye-bye, Kerensky...
- Bye-bye, Countess...
- Scaroth was planning to do this to all of humanity.