->''If you could touch the alien sand, and hear the cry of strange birds, and watch them wheel in another sky, would that satisfy you?''
-->-- '''Part Two - "The Cave of Skulls"'''
We commence with the World's Trippiest TitleSequence and the first time an audience would hear the "Oooh-ee-oooh" of the theme tune. [[note]]Don't believe us? [[http://www.youtube.com/watch?v=75V4ClJZME4 watch this]] (with about two minutes worth of unused footage).[[/note]]
Two teachers, Barbara Wright and Ian Chesterton, think their super-bright pupil, Susan Foreman (a brown-eyed girl, complete with transistor radio), is a bit on the strange side. She's bored with regular physics and math and wants to move on to multidimensional physics and maths, and she thinks that the UK has decimalised its currency (which hasn't yet happened in 1963)[[note]]Britain would decimalize the pound in February 1971, after a few years of preparation. Amusingly, at the time this serial aired, pretty much all of the rest of the Commonwealth had either already decimalised (South Africa) or was in the process of doing so (Australia, NZ)[[/note]]. So, they decide to follow her home one night. This being 1963, it's benign concern for the welfare of a child, and [[ValuesDissonance not at all creepy]].
They arrive at Susan's home address of 76 Totter's Lane. It's a junkyard. They hear Susan's voice coming from inside a police box. Thinking that her grandfather, "I. M. Foreman", has locked her in there, they proceed to open the door and enter the TARDIS. Which is bigger on the inside than out. Her grandfather, a crotchety old man, is the Doctor.
Deciding that he can't have them tell the world about the CoolShip and that the "Foremans" will need to leave the 1960's again, he starts up the TARDIS, acquiring the first two companions via abduction. Ian and Barbara are knocked unconscious by the time travel.
When they've landed again, the foursome step out of the TARDIS and Susan quickly exposits that it was supposed to have changed shape: the first clue that it's somewhat less than reliable. Before long, the Doctor is kidnapped by a tribe of cavemen when they see him smoking his pipe [[EarlyInstallmentWeirdness which he never smokes again]]. This tribe has lost the ability to make fire, and the Doctor agrees to placate them by giving them fire, but unfortunately he has lost his matches. His three companions try to rescue him, but only succeed in getting themselves captured too. In the middle of all that, the Doctor decides to simply kill a friendly but wounded cavemen who's slowing them down a bit. This earns him his first ever WhatTheHellHero from Ian, who prevents the murder. The tribe of primitive humans with monolithic names keep their captives in a cave full of skulls, skulls that have been obviously split open. Charming.
A friendly (well, less hostile) tribesperson unties them, and they make tracks. Eventually, the Doctor tricks the hostile aspiring caveman leader into admitting he's a murderer, Ian gives the less hostile aspiring caveman leader the gift of fire, and they all escape back to the TARDIS. But since they had to take off in a hurry on account to avoid being speared, the Doctor was unable to make the calculations necessary to chart a course back to 1963. Hopefully their next landing spot will be a bit less eventful...
NB: This story is commonly also called "100,000 BC", and less commonly called "The Tribe of Gum". "An Unearthly Child" is the title of the first episode (episodes were individually named until season 3) and is applied to the entire first serial through synecdoche.
* AccidentalMisnaming: Ian is known to the tribe as "Friend".
* ActionGirl: Susan attacks one of the cavemen with a rather disturbing enthusiasm.
* BigBad: Kal, the first in a long line of ''Doctor Who'' villains and the person responsible for its first two deaths before becoming the third.
* CharacterizationMarchesOn: In one episode, the Doctor -- y'know, the poster boy for [[TechnicalPacifist Technical Pacifism]] -- is apparently prepared to bash a helpless man's head in with a rock... because Barbara's insistence on caring for his wounds is slowing them down as they try to escape.
** Though it's been theorized that this is precisely the moment that started his love for humans, realizing how they kept him from slipping into villainy.
* DeadpanSnarker: Horg.
* FailedASpotCheck: The Coal Hill school nurse has failed to notice that Susan has a body temperature of sixty degrees and [[Recap/DoctorWhoS14E6TheTalonsOfWengChiang a curious double heartbeat]].
** Not really, as at this time the doctor only had a single heart as well, it was established later in the series that time lords had two hearts, and the they only gained the second one AFTER their first regeneration.
** It would be more accurate to say that the fact Time Lords have two hearts wasn't established until later in the series. WordOfDante says that the Doctor only had one heart at this point but there's been no firm evidence either way in canon and the ExpandedUniverse tends to flip flop on the subject (one novel explicitly states the First Doctor only had one heart, another has a character notice something strange but unspecified about his pulse, and a third flat out states Susan has two hearts).
* FamilyUnfriendlyViolence: The oft-quoted truism that Doctor Who was originally supposed to be an educational programme for children seems somewhat dubious in light of this story. There are a lot of dark, violent themes and moments, such as the sight of Za's slashed up, bloody chest after an animal attack, the Doctor trying to smash open the head of an injured man and the heroes being trapped in a cave full of broken skulls, foreshadowing their possible fate. The most shocking part is a lot more subtle however, as Ian and Barbara's attempt to get a policeman, and in particular their fear of what the Doctor might be doing to Susan in the mysterious blue box imply that they (wrongly) fear he may be molesting her.
* FutureImperfect: What draws the teachers' attention to Susan. Susan mixes up a question about British currency, due to forgetting she's in a time period before it switched to a decimal system. (This did indeed happen.)
-->'''Ian:''' "You're treating us like children!"\\
'''The Doctor:''' "Am I? The children of ''my'' civilisation would be insulted."
* LineOfSightName: It is implied that Susan got her last name from the junkyard where she and her grandfather were hiding out.
* NeverMessWithGranny: The oldest cavewoman is also the most vicious, and the most politically adept schemer.
* NotThatKindOfDoctor: When the Doctor is refusing to help Ian and Barbara administer first aid to the wounded Za, Barbara points out that he's a doctor, and he says that he isn't a medical doctor.
* OneMillionBC: Though an alternate title for this story is 100,000 BC.
* ScreamingWoman: Justified in the case of Susan; she's incredibly sheltered and repeatedly shown to be nervous and easily intimidated, and has been raised by the Doctor to view the outside world as an inherent threat. And, of course, she's also a ''child''; younger [[ReallySevenHundredYearsOld by Gallifreyan standards]] than human ones, and even a shy human teenager could be forgiven for screaming while being kidnapped by cavemen.
** It could be argued that applying this trope to Susan is unfair; she screams quite often, but is also shown to be remarkably intelligent, perceptive, and generally a very useful person to have around.
* ShakyPOVCam: Used to represent the jungle cat that attacks Za.
* StyrofoamRocks: Naturally, as the whole thing was filmed in a studio (and really looks it).
* TheHeart: Arguably, Susan's role; her frantic pleading for leniency on the part of the intruders is what eventually softens her grandfather toward them, and the only thing Ian, Barbara and the Doctor are in complete agreement about is that protecting and caring for Susan is of the utmost importance.
* TheTheTitle: Individual titles for each episode mean that we get "The Cave of Skulls", "The Forest of Fear" and "The Firemaker". Also, "The Tribe of Gum" was a working title (although the naming convention used in those early days would have properly named it "Doctor Who and the Tribe of Gum")
** Ian addresses the Doctor as "Dr. Foreman"; the Doctor responds, "Eh? [[ThrowItIn Doctor who]]?"
** Then, later, Ian to Barbara: "Who is he? Doctor who? Perhaps if we knew his name, we might have a clue to all this."
** This all becomes the setup for the show's current longest-running BrickJoke -- which was first alluded to again in "The Girl In The Fireplace" ("The Doctor? Doctor ''Who''? It's more than just a question, isn't it?"), and would finally land in the 2013 anniversary season finale episode "The Name Of The Doctor".
* WhatTheHellHero: Ian calls the Doctor out for his aforementioned attempted rock bashing.