At the outbreak of the First World War three cousins reigned over Europe's greatest powers - Tsar Nicholas II of Russia, Kaiser Wilhelm II of Germany and King George V of Britain. This two-part series looks at the role played by the three monarchs, and their relationships with each other, in the outbreak of war, arguing that it is far greater than historians have traditionally believed.

The first episode tells the story of the emerging divisions and rivalries between the interrelated royal houses of Europe and features the little-known story of the two Danish sisters, Princess Alexandra and Princess Dagmar, who had pulled off the dynastic coup of the 19th century by marrying the heirs to both the British and Russian thrones. Following the invasion of their native Denmark by Prussia in 1864 during the Wars of German Unification, the sisters became the core of an anti-Prussian coalition that prefigured the great anti-German alliance of 1914. Their sons, King George V and Tsar Nicholas II were close friends.

It looks too at the tangled relationship between the German Kaiser and his English mother, Vicky - the oldest daughter of Queen Victoria. Disabled from birth, Kaiser Wilhelm had a complex love/hate attitude towards Vicky, which transferred itself to Britain as a whole, strongly influencing his foreign policy.