-->''Have you never looked back over the course of your lives, sirs, and sincerely wondered if you had truly made any difference at all in the grand scheme of things? What if you could find out, could live long enough to see the greater picture?''
-->--'''Nikola Tesla'''

When the Doctor takes Holmes and Watson to Niagra Falls earlier in their own year to visit NikolaTesla, they naturally get more than they'd bargained for. Tesla has built a machine meant to grant longevity or even immortality, and when he tests it ''on himself'', the machine ''does'' [[GoneHorriblyRight Go Horribly Right]]. Now it's up to the time travelers and inventor George Westinghouse to protect Tesla from a resourceful foe...

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!!This Episode Provides Examples of:

* BavarianFireDrill:
-->"Ah, hello, sorry about that! Detective Inspector Smith, Scotland Yard. Been chasing a couple of anarchists all the way from, well, Scotland, matter of fact! Attempted murder, you see."
* BeethovenWasAnAlienSpy
* BerserkButton: Oh, dear ''Lord'', do ''not'' mess with the TARDIS!
* BreakTheHaughty: Tesla experiences this very quickly...
* ContinuityNod: To [[Recap/ChildrenOfTimeS1E1SmithAndHolmes "Smith and Holmes"]] once again when the Doctor explains what Rift Matter is.
** And, almost in the same breath, the Cardiff Rift.
** Plus, Torchwood and the events of "Tooth and Claw".
** Also, the Companions have a bit of a flashback upon arriving at Niagra Falls, the first time they've visited a waterfall since May 1891.
* EvilIsNotWellLit: Justified, as per TheUnreveal below -- the mystery figure cloaks his identity physically with shadows.
* {{Foreshadowing}}: [[spoiler:Tesla's experiment]] and [[spoiler:the Cardiff Rift]] are going to be ''very'' important later...
** Plus, Nikola's final telepathic conversation with the Doctor.
* FountainOfYouth: The intention for Tesla's invention.
* GoneHorriblyRight: Tesla's machine ''does'' provide longevity... [[spoiler:by returning the person inside to childhood]].
* HeterosexualLifePartners: Nikola Tesla and George Westinghouse, with Westinghouse implied to be the "Watson" in their friendship.
** Which is toted by the characters themselves as a good thing, until [[spoiler:Jones suggests to his employer that they may be able to use Tesla's friendship with Westinghouse against him in the future]].
* HistoricalHeroUpgrade: George Westinghouse.
* TheKnightsWhoSaySquee: Holmes gets this treatment this time -- well, about as much as Sherlock Holmes will ever "squee"...
* MeaningfulName: The operation is named "Icarus" -- the original Icarus, well... things didn't work out so well for him.
* MerlinSickness
* NoOSHACompliance: Lampshaded by the Doctor in analyzing Tesla's machine aloud... "Your control console isn't quite there yet -- you've accounted for time and intensity but not pressure, temperature, radiation... Not even a safety gauge to alert when something malfunctions."
* NothingIsScarier: Who's the figure in shadows at the end? We don't know. ''And neither does Peterson''.
* {{Pride}}: Tesla's biggest failing, best seen in this quote:
-->Doctor, please! This is humanity’s best opportunity to evolve, to transcend our limitations – you can’t take that away from me...
* ProfessorGuineaPig:
-->"Them," sir? How could you think I would ask anyone to be subject to such a process without first carrying it out on myself?
* ReasonableAuthorityFigure: George Westinghouse.
* SequelHook: The last chapter and the epilogue.
* TheUnreveal: Peterson's employer.
** This is the second episode to introduce an unresolved mystery to the series -- like Kit's identity in "The Manhattan Conspiracy," the identity of the Torchwood mystery man won't be revealed until the season finale.
* WhatTheHellHero
-->"And what about Nikola, Doctor--doesn't he have a say in this? You haven't even asked him whether he wants to be turned back!"
* WhoWantsToLiveForever
* YouHaveFailedMe: Invoked by the shadowy figure in the epilogue.
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