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.
A disgraced merchant marine officer elects to stay aboard his sinking cargo ship in order to prove the vessel was deliberately scuttled and, as a result, vindicate his good name.
Matt Braddock is a civil engineer during World War II who has new ideas for shipbuilding. Braddock tries to establish yards for building prefabricated ships on the West Coast, but he is hindered by the former superintendent of the shipyard, Joel Kennedy. A disappointed lover fails to deliver an important message on welds and it leads to the collapse of a new ship's superstructure and the death of a boy.
