During the last days of July 1914 telegrams flew between the King, the Kaiser and the Tsar. George V, Wilhelm II and Nicholas II, known in the family as Georgie, Willy and Nicky, were cousins. Between them they ruled over half the world. They had been friends since childhood. But by July 1914 the Trade Union of Kings was falling apart. Each was blaming the other for the impending disaster of the First World War. 'Have I gone mad ' Nicky asked his wife Alix in St Petersburg, showing her another telegram from Willy. 'What on earth does William mean pretending that it still depends on me whether war is averted or not!' Behind the friendliness of family gatherings lurked family quarrels, which were often played out in public.

Drawing widely on previously unpublished documents, this is the extraordinary story of their overlapping lives, conducted in palaces of unimaginable opulence, surrounded by flattery and political intrigue. And through it runs the question: to what extent were the King, the Kaiser and the Tsar responsible for the outbreak of the war, and, as it turned out, for the end of autocratic monarchy.