Four years after the Titanic sank, the world was rocked once more by the sinking of the RMS Lusitania in 1915. This time it wasn't an iceberg that was to blame rather a German U-boat that torpedoed the ocean liner 11 miles off the southern coast of Ireland. It resulted in the deaths of 1,198 passengers and crew and was a key factor in the US's entry into the First World War in 1917. The events of that day are brought to life in this documentary using archive footage, photographs, documents, dramatic reconstructions and expert opinion by marine historians, as well as first-hand testimonies by survivors and the submarine captain.