Using elaborate re-enactments, fascinating Computer Generated Imagery and previously unseen archive footage the programme examines how the assassination in Sarajevo in 1914 came about and how Austria-Hungary used the death of the heir to the throne, Franz Ferdinand, to start a war against Serbia. The film investigates how this regional conflict caused the Central Powers and the Triple Entente to enter the First World War - at the time, the biggest war in history with 17 million soldiers and civilians killed and more than 20 million injured.