A down-and-out crook on the lam befriends a young street urchin, in an Italian port city. At first amused that the boy is a sneak thief, he tries to deflects the kid from a life of crime. Tipped off by a woman anxious to collect the reward for him (who is wanted for murder), the police pursue the two lost souls.

In Tiger Bay, the docklands of Cardiff, rough-and-tumble street urchin Gillie witnesses the brutal killing of a young woman at the hands of visiting Polish sailor Korchinsky. Instead of reporting the crime to the authorities, Gillie merely pockets a prize for herself — Korchinsky's shiny black revolver — and flees the scene. When Detective Graham discovers that Gillie has the murder weapon, the fiery young girl weaves a web of lies to throw him off course.