Frankie Palmer is a normal, lovable boy who one day catches sight of a yellow balloon in a shop window. Procuring the money from his impoverished father, Frankie sets on his way to buy the balloon, but drops the sixpence, which rolls down the drain. When he sees his friend Ronnie has purchased the balloon, he playfully snatches it away and a wild chase follows up and down the rickety skeleton of a blitzed building. Their chase ends in a terrible accident, witnessed by the unscrupulous Len Turner, who takes advantage by blackmailing young Frankie, convincing him he faces criminal charges. Too terrified to confide in his parents, Frankie becomes a pawn for Turner, coerced into a robbery that ends in murder.