A policeman investigates an eerie scrap merchant's yard on Totter's Lane and finds a police box. It hums and flashes strangely.
At a small school, two teachers discuss a strange 15-year-old student, Susan Foreman. Barabara has tried to check on her but thinks Susan has given a fake address. They follow her after school to see where she goes, discussing more oddities – she doesn't understand the British monetary system, yet her knowledge of science appears to be way beyond even Ian's professional training.
When Susan appears, they follow her into the scrap yard but she has vanished. They find the humming police box and an strange old man arrives and attempts to enter it. They ask him where Susan is but he defiantly tells them to leave. Before they do, Susan comes out of the police box. The teachers rush past the old man and discover a vast futuristic control room.
Susan and her grandfather are upset that they've been discovered. They explain that the room is the center of a vehicle called the TARDIS which travels in Time and Space. Ian and Barbara don't believe them but the old man decides he can't risk their knowledge of his TARDIS and takes off. The police box appears on windswept plain. And a shadow approaches it.