STORYLINE
Ian Chesterton and Barbara Wright are two teachers who seem to be getting frustrated by an enigmatic student of theirs. Susan Foreman, in some cases is exceptionally bright, sometimes to the point of overshadowing her teachers, but on occasion she has shown a lack of knowledge of the basics, such as the currency that England uses.
For some reason the two teachers decide they need to butt into Susan's business and follow her home in order to talk to her grandfather. Instead they see her enter a junkyard. When they follow her inside there is no sign of her. They do find, however, a strange, vibrating police telephone box.
They hear Susan inside, and when her grandfather returns they barge past him and into the police box - where they find a large, brightly lit, room with a mushroom shaped console in the center. The Doctor is not happy at the intrusion, and says that if he lets them go free they will inevitably tell someone about what they saw. Before anyone can stop him the Doctor dematerializes the TARDIS.
It re-materializes around 100,00 B.C. where they are promptly caught and held captive by a group of primitive men. It seems these early cave men are having trouble creating fire, and they believe the Doctor can make fire for them. After nearly being killed by these primitives, the group is able to escape and make its way back to the TARDIS.
The Doctor attempts to take the teachers back to their own time, but materializes on an unknown world.