Britain's Coastal defence barriers revealed to public.
Full title reads: "DEFENCE BY FIRE".
This film deals with the various methods used by the Petroleum Warfare Board to prevent the German invasion on the British Isles.
Shots are mainly big fires on the sea coasts of Great Britain with huge palls of black smoke. The 'Fougasse', an innocent looking tar barrels filled with petrol were hidden along the cost ready to blast. Several shots of the barrels blasting. Antiaircraft flame throwers shooting flames vertically are seen.
Final shot shows a quiet beach scene with small waves breaking gently on a beach.