In the summer of 1929, Weimar Germany's secret military agreement in the 1920s with the USSR to evade the Versailles Treaty and develop new weapon systems beyond the Ural Mountains is about to bear fruit. Aided by a shadowy international conspiracy of arms dealers, industrialists, and financiers, both countries are poised to dismember the newly independent Poland created in the aftermath of the Great War. To distract Britain from helping the Poles and risking a new world war, the conspiracy intends to foment a coup d'etat in the Irish Free State, the newest member of the British Commonwealth whose 1922 civil war with the IRA is a fresh memory.

Meanwhile, on the eve of a long holiday in North America after his Tory party lost an election, the former Chancellor of the Exchequer, b>Winston Churchill,receives a clandestine assignment from the new Socialist Prime Minister Ramsay MacDonald. The British Secret Intelligence Service (SIS) has learned the IRA is about to buy a massive amount of arms in the United States to facilitate their coup d'etat in the Irish Free State. MacDonald is sending a team of SIS agents to the United States to investigate and document the IRA's plans. He asks Churchill to use the SIS information to persuade the U.S. President Herbert Hoover to stop the arms from leaving the country.

But a cautious Churchill, wary of anti-Irish Free State sentiments in the SIS, assembles his own private team to conduct a parallel investigation.