Doctor Who and an Unearthly Child — Terrance Dicks

Ian and Barbara refuse to believe that the Doctor can travel through time, so he takes them into the past where they meet up with a tribe of cavemen. The tribe has lost the ability to make fire and the Doctor must decide whether to give it back to them. To make matters a bit more confusing there are two warriors jockeying for leadership of the tribe, so the Doctor needs to decide who to present it to. Oh, and of course everyone is threatening to kill the Doctor and his companions if they do not do what they are told.