Barbara and Ian

Schoolteachers Barbara Wright and Ian Chesterton become intrigued by the strange behaviour of one of their pupils, Susan, who seems to have a very alien outlook on England. She is precocious but seems to have strange gaps in her understanding of the world. They decide to visit her home address so that they can meet her grandfather.

Her address, 76 Totter's Lane, turns out to be a junkyard. As they look around the only thing that looks out of place is a police telephone box. They then hear the sound of someone approaching. This turns out to be an old man. As he enters the junkyard, unaware that Barbara and Ian are watching him from their hiding place, he unlocks the door to the police telephone box.

They then hear the sound of Susan’s voice coming from within the police telephone box. Concerned that something is wrong Barbara and Ian confront the old man. He denies having heard anything and mocks Ian when the schoolteacher suggests that Susan is inside.

Susan

As they seem to be getting nowhere the school teachers decide that the need to obtain the services of a policeman. However, when Susan’s voice is heard again calling out for her grandfather, the two schoolteachers barge past the old man and enter the police telephone box.

When the two schoolteachers find themselves inside they are confronted with a room that is much bigger on the inside than the outside, and furnished with futuristic-looking controls. Unknown to the two schoolteachers the old man is in fact The Doctor and both he and Susan are in fact aliens who travel through time and space in their ship, the TARDIS which just happens to look like a police telephone box.

Barbara and Ian watch The Doctor Enter the Police Box

Barbara and Ian are naturally, taken aback by the strange and seemingly impossible surroundings. They start to question The Doctor and Susan in an attempt to make sense of everything. They then realise that they are trapped inside this strange, futuristic place.

The Doctor, it seems, is unwilling to let them go as he is concerned that they will inevitably tell others what they have discovered. Susan pleads with him to change his mind, but instead he activates the ship's controls and sends the TARDIS on a journey through time where the ship arrives in the Stone Age.

On exiting the TARDIS the four occupants become involved in a brutal power struggle within a Stone Age tribe, who are striving to rediscover the lost secret of fire. After being captured and imprisoned in the Cave of Skulls they eventually manage to escape by scaring the tribes-people by placing skulls on top of burning torches. This induces fear and respect in the primitive Stone Age society.

Barbara, Ian and The Doctor Outside the TARDIS

The four travellers make good their escape but they barely escape with their lives reaching the safety of the TARDIS just before the angry tribe catch up with them. Relieved that they all made it back to the time machine The Doctor again activates the controls.

They soon arrive at a new random destination. But even The Doctor does not know where or when. The TARDIS's view screen shows a mysterious scene, a petrified forest and none of the monitors warn of any danger. However, as the time travellers leave the TARDIS, they are unaware that the needle, on a radiation meter, starts to move until it is registering "Danger".