Doctor Who: An Unearthly Child (1963), Chapter 4: “The Firemaker”
So the Doctor, Susan, Ian and, um, whatsherface, the useless one… Barbara! That’s it! Anyway, they, along with Za and Hur, get surrounded by the cavepeople as led by Kal. Za’s still mostly unconscious thanks to his run-in with the Beast Beyond the Budget, and Kal sneers at the fact that Za is so weak that his woman has to speak for him. Kal also takes the occasion to accuse Za of killing the old woman while he helped the time travelers escape. There is, however, no blood on Za’s stone knife, and when the Doctor tricks Kal into showing his own knife, there’s blood all over it. Faced with the evidence, and bereft of the protection of Miranda Rights, Kal admits that he killed the old woman himself because she let the time travelers go.

The Doctor then rallies the tribe against Kal, pointing out that he could kill any one of them whenever they stand in his way. They start pelting Kal with stones and drive him out, and in gratitude… Wait, they haven’t invented gratitude yet. So the freshly-revived Za orders the four to be dragged back to the Cave of Skulls, and this time guard BOTH entrances, thank you very much! Because he still needs the secret of fire to cement his leadership.
Which secret, frankly, any of the time travelers would be happy to share, if only people would stop locking them in caves and threatening to sacrifice them to Orb. Just to demonstrate it, Ian spends his time putting together a bow-driven firestarter kit, and putting some elbow grease into the good ol’ friction method. Frankly, it’s fortunate that at least one of them has the skills necessary to start a fire from scratch; I think that most of us, if transported to the paleolithic age, would have a hard time demonstrating personally any of the great advances of our culture and science (aside from, “And now listen to THIS ringtone!”).

When Za comes to check on them, he is of course entranced by the fire that springs up for Ian. But the Doctor’s enlightened ideals — that everyone should know the secret of fire, so that it won’t get lost again — fall on deaf ears, because Za’s got so much invested in that whole “cementing my leadership” thing. Boy, good thing we’ve evolved beyond that, huh? He’s further distracted from egalitarian social policy by Kal, who has managed to sneak up and dispose of the guard posted at the no-longer-secret entrance. What follows? Ultimate Caveman Fighting! While the time travelers mostly try to stay out of their way, Za and Kal roll around the cave, biting and scratching, until Za finally heaves up a stone and jellies his opponent’s head. (Guess that’s one skull that’ll be in no condition for storage in the Cave of Skulls.) After such a demonstration, the Doctor apparently thinks better of reasoning his way out with Za.

Za takes a burning brand out of the cave to start the tribal fire, and in gratitude… Wait. Sorry. He orders the four to be kept captive longer, intending eventually to assimilate them into the tribe and thus take advantage of any other nifty things they may know. So then Susan hits on an escape plan which would have no chance of working if the Mighty Scriptwriter Gods didn’t decree that it would: She sticks a flaming stick, soaked in the fat of the bits of meat that they’re given to eat, up inside a handy skull.

(I’m a little tired, kids; make your own Ghost Rider joke here.)
How does this help them escape? Well, they make a few of them and set them up in the cave. When Hur comes in to check on them, she sees the flaming skulls and, I dunno, goes into some sort of superstitious conniption. The rest of the tribe comes when she screams, and all of them collapse in moaning wonder at fire! In skulls! Ian leads the others out the back way and they scamper through the forest. Za realizes that they’ve just been taken in by the World’s First MacGyverism and leads the chase after them, but this time the travelers make it back to the T.A.R.D.I.S. and send it spinning into the time-space stream just before the spears start to land where it had been sitting.

Which would pretty much be the entire story, except these early storylines weren’t really constructed as discrete storylines, so we get a few minutes setting up the next phase of the show: Because the Doctor really didn’t know exactly where/when they were, he couldn’t easily set the T.A.R.D.I.S. to get the schoolteachers back where they started from. Plus, they were trying to get out of PaleoVille in all due haste. Plus, he’s really not the best T.A.R.D.I.S. pilot in the universe (which might explain why he stayed in a salvage yard in 1963 London for months on end). So they arrive… somewhere else. Somewhere with huge bamboo-like plants growing in a misty swamp. Somewhere that sets the unnoticed radiation detector needle over in the red.
But that’s a story for another time.
Next Week: Something Completely Different!