Steven Moffat once said that when you write a Doctor Who story, you give up your feature film idea, so rapacious is the series’ appetite for strong, action filled plot. It was never truer than of City of Death, which has a plot almost too good for Doctor Who – an alien splintered through time plunders the art treasures of the world in a plan to go change history. A Doctor-less version would make a cracking popcorn movie, full of action, comedy and romance. The Thomas Crown Affair meets Back to the Future. Moff should make it now his showrunning days are done.

This story, in which Exec Producer Julie Gardner saw a template for 21st century Who, is one of the series’ undisputed triumphs. It was born from a last minute script crisis and a mammoth weekend-long rewriting session by Douglas Adams and Graham Williams, fuelled by coffee, whiskey and desperation, but emerged as an elegant European supermodel of a Doctor Who story. With location filming in Paris, a whip smart script and performances to match, it’s a piece of art.

And of course, it’s funny. A Doctor Who parlour comedy. But to talk about how funny it is would be to repeat everything that has ever been written about it. So instead, let’s talk about how it works as a piece of drama, because it absolutely does.

Here’s my favourite piece of dialogue from it. It’s got nothing to do with Paris telephone directories, violent butlers or beautiful women, probably. The Doctor (Tom Baker, at maximum power) and Count Scarlioni (Julian Glover) have been firing one liners at each other for four episodes. Now the climax is approaching, and the Doctor has realised (somehow) that if the Count goes back in time to prevent his own destruction, the human race will never evolve. Suddenly the funny stuff drops, and both play it dead seriously.

DOCTOR: Count, do you realise what will happen if you try to go back to the time before history began?

SCARLIONI: Yes. Yes, I do. And I don’t care one jot.

I love the wit of City of Death, but I love these moments of sudden sobriety just as much. Take for instance, the cliffhanger to Part Two. Once again it’s an abrupt change from jokes to gravitas. The Doctor has travelled to Florence in 1505 to find out if Leonardo really did paint seven Mona Lisas and to swap gags with a dopey guard (Peter Halliday). The Doctor’s laughing off having a sword at his throat, but when a door opens and a shadowy figure looms. His levity’s instantly turned off.

DOCTOR: You. What are you doing here?

SCARLIONI: I think that is exactly the question I ought to be asking you… Doctor!

It’s one of those beautiful cliffhangers that progresses the plot as well as leaving us begging for more: how can Scarlioni be in both 1505 and 1979? And its Part Three equivalent is equally impressive and far more grim. Scarlioni convinces the hapless Kerensky (David Graham) to step inside his time bubble. With trademark urbanity, the Count tells Romana (Lalla Ward) “You will now see, my dear, how I deal with fools.”

He speaks not with the grandiose roar of a standard Doctor Who villain left in charge of an episode ending, but with chill politeness. He switches on the machine and Kerensky ages to death. Then, pre-closing credits, he smiles smugly at Romana, as if to say, “aren’t I clever?” It’s the understatement of it which makes it work.

Think also about Countess Scarlioni (Catherine Schell), a guileless dupe of her husband. Up until Part Four the Doctor’s been content to humour her, but time is running out and everyone’s about to die. He asks how much she knows about the Count and she mentions the importance of discretion and charm. Baldly, the Doctor calls her out.

DOCTOR: There is such a thing as discretion. There’s also such a thing as willful blindness.

COUNTESS: Blind? I help him to steal the Mona Lisa, the greatest crime in the century, and you call me blind?

DOCTOR: Yes! You see the Count as a master criminal, an art dealer, an insanely wealthy man, and you’d like to see yourself as his consort. But what’s he doing in the cellar?

COUNTESS: Tinkering. Every man must have his hobby.

DOCTOR: Man? Are you sure of that? A man with one eye and green skin, eh? Ransacking the art treasures of history to help him make a machine to reunite him with his people, the Jagaroth, and you didn’t notice anything? How discreet, how charming.

She tries to laugh it off, but then recalls an old Egyptian scroll parchment in her collection. On it, a man with one eye and green skin. The spell is broken.

And although she’s been played for a fool by Scarlioni, he still feels fondly enough of her to come and say goodbye to her before setting off to erase all mankind from history. She’s ready to shoot him, but can’t quite do it. He gets to her first, but not before he’s coldly dismissed her, as nothing but a money loving dilettante. “It has not been difficult keeping secrets from you, my dear,” he matter-of-factly states. “A few fur coats, a few trinkets, a little nefarious excitement.” Then he zaps her. Not much to laugh at there.

And that’s fine. In fact, it’s better than fine, it’s exactly right. Because Adams and Williams knew that the best stories aren’t just funny, or just scary or just sad. They are all of the above. So here they turn up the dial on the funny, while leaving the scary and sad controls on their standard settings. It’s just dumb luck that they happen to perform this experiment on one of Doctor Who‘s best ever ideas.

Composer Dudley Simpson gets it. To accompany that glorious last shot from the top of the Eiffel Tower, gazing down at the Doctor and Romana running from the scene of the crime, he provides a musical finale which sums up the story perfectly. A whimsical clarinet picks out a charming melody, before it slips into a minor key, getting serious. Then a low, ominous sting to end the story, bass notes and timpani drums. He’s summed this story up completely. For all its lightness of tone, the darkness is always right behind.

LINK TO Asylum of the Daleks. Both refer to the Daleks and Skaro.

NEXT TIME: what is this horrendous place? Next stop, Terminus. And probably a bit more about City of Death.

AND ONE LAST THING: I’m indebted to @EalaDubh for pointing out this about City of Death, which I had not previously known and is now one of my favourite things.