On a day trip to London with her Aunt Lavinia in November 1963, Sarah Jane, a young girl with an enquiring mind, nips off to explore while her guardian goes off to buy sweets for her. Behind some double gates she finds a junkyard full of shop window dummies, broken chairs, picture frames and, strangely, a police box. Lost in her own world, during which she briefly pretends to be a reporter at one point (thus sowing the seeds for her future career!), she suddenly remembers her aunt and races off as a car pulls up and an older girl runs into the junkyard.