Doctor Who/Recap/S29/E06 The Lazarus Experiment

"Martha: "What'd he do?"

The Doctor: "Changed what it means to be human.""

The Doctor, wary of getting too attached to another human, or perhaps of getting another human killed, or maybe just enjoying the way he toys with Martha's emotions, drops Martha off back home. Her time in the TARDIS over. However, he realizes that that Martha's time period is in danger, and returns only seconds after he left for -- ostensibly -- one more adventure with Martha.

The activity in question is that of Richard Lazarus (Mark Gatiss), a brilliant scientist, who has devised a way to reverse the aging process. The scientist tests his equipment on himself at a black tie affair (Martha and the Doctor were invited at the last minute, which will be explained in later episodes). When Things Spin Science Happens, and Lazarus successfully turns himself into a young man. Martha's sister, who works at the center, just mysteriously got a huge promotion and is happy to see her boss now looking very young and handsome and snoggable indeed.

Meanwhile, Martha's mum is approached by a suit-wearing guy, who hints that the Doctor is dangerous. He is 100% right about that, but the soundtrack doesn't like him, so neither do we.

Then Lazarus surprises everyone by turning into a massive CGI scorpion monster thing! Martha's sister laments that she was going to snog him.

The Doctor kills the scientist with the polarity-reversed age-reversal machine. The scorpion beast turns out not to be dead after all and flees to a cathedral, where the Doctor kills it again with. For real this time.

And finally, finally, the Doctor stops yanking Martha's chain and lets her come aboard full-time.

But as the TARDIS takes off, Martha's mum leaves a message on the answering machine not to be with the Doctor, saying the notice came from Harold Saxon...

Tropes
"The Doctor: "A science geek?" What's that mean?
 * Arc Words: Lazarus's experiment has some involvement with Mr. Saxon, and the man who warns Martha's mother about the Doctor is revealed to be working for him as well.
 * Big Red Button: pressed with an unusual lack of ceremony.
 * Chekhov's Gun: The cathedral is mentioned in the roof scene.
 * Conspicuous CG: The monster itself looks pretty good, but its face looks almost two-dimensional.
 * Continuity Nod: Martha calls the Doctor her "plus one".
 * The Doctor muttering to himself over being slapped by his companion's mother.
 * The Doctor complaining that something bad always happens when he wears a tux.
 * Delayed Reaction: The Doctor sees Lazarus's press conference without commenting, leaves in the TARDIS, and then comes back to double-check what he just heard with Martha.
 * Digging Yourself Deeper: The Doctor puts his foot in it talking to Martha's mum and gives her the impression that he's sleeping with her.
 * Dying As Yourself
 * Follow the Chaos: Martha finds the Doctor by running towards the sound of the explosions.
 * Foreshadowing: The somewhat sinister agent of Harold Saxon who warns Martha's mother that the Doctor is dangerous.
 * The emblem hanging on most of the walls is the same as
 * Fountain of Youth
 * Game Face: Early on in Lazarus' mutation.
 * Gone Horribly Wrong
 * Insult Backfire

Martha: Means you're obsessively enthusiastic about it.

The Doctor: *happily* Oh, okay!"

"Francine: Busy? Doing what, exactly?
 * Innocent Innuendo: The Doctor causes a few awkward moments talking to Martha's mother by saying he and Martha haven't had much time to talk as they were "busy". Fortunately, their conversation is interrupted before he can dig himself deeper.

The Doctor: Oh... you know... stuff."

"The Doctor: You can't control it, the mutation's too strong. Killing those people won't help you. You're a fool. A vain old man who thought he could defy nature, only nature got her own back, didn't she? You're a joke, Lazarus! A footnote in the history of failure!"
 * Involuntary Shapeshifting: Lazarus constantly shifts between that... thing and his youthful human form due to an Unstable Genetic Code.
 * Liquid Assets of the Life Energy variety: What mutant!Lazarus feeds on.
 * Loud of War: Sonic screwdriver plugged into cathedral pipe organ = this trope.
 * Mad Scientist: The classic story of a deluded scientist who ends up turning himself into a monster.
 * Meaningful Name: In the Bible, Lazarus was the man raised from the dead by Jesus.
 * Which the Doctor neatly lampshades at one point.
 * Monster Sob Story: Lazarus is a Complete Monster who ruthlessly murders others to prolong his life, but you can somewhat sympathise with his sheer determination to conquer death.
 * Names to Run Away From Really Fast: The Lazarus Project. That's not going to go well.
 * Except when it did go well.
 * Never Be Hurt Again: Lazarus wants to avoid death because of his experiences during World War II.
 * No Transhumanism Allowed
 * One Winged Angel
 * Professor Guinea Pig
 * Reverse the Polarity: Mentioned by name. The Doctor says "It shouldn't have taken me so long to reverse the polarity, I must be out of practice."
 * The Reason You Suck Speech


 * Shaky POV Cam
 * This Was His True Form
 * Unstable Genetic Code: Lazarus. And yes, Martha the med student points out the sheer impossibility of this trope.
 * Up to Eleven: The Doctor invokes it by name.
 * When Things Spin Science Happens
 * Who Wants to Live Forever: A central theme. Having barely survived the Blitz as a child. Lazarus has been obsessed with conquering death all his life. However, the Doctor informs him that being immortal in a world of mortal things is not fun at all.
 * Your Princess Is in Another Castle: Lazarus is carted away in an ambulance... and there's almost 15 minutes left of the episode. Hm.