The introduction of submarine warfare in the First World War: LS of squadron of German warships. Cut to shots of British naval officers coming aboard one of their ships, saluting and posing under a battery gun. LS of freighter at sea, a U-boat surfacing in the foreground. MLS of U-boat ploughing through the waves, MCU of torpedo wake, MLS of freighter exploding when hit. Various shots taken from on board U-boats of vessels sinking. Two MLSs of "Lusitania" leaving New York; CUs of newspaper headlines announcing that the vessel has been sunk.