In the summer of 1929 Weimar Germany still has a secret military agreement with the USSR to develop new weapons beyond the Ural Mountains. Ultimately, both want to dismember the newly revived independent Poland, but to distract Britain from helping the Poles, the new Irish Free State is placed at risk by conspirators and arms dealers intent on fomenting an IRA coup d'état.

Winston Churchill is about to travel to North America when the new Prime Minister Ramsay MacDonald asks him to handle a secret assignment. The IRA intends to buy large quantities of arms in the United States and an SIS team will investigate. Churchill is to enlist American President Herbert Hoover to prevent the weapons from reaching Ireland. But Churchill has his own unofficial team gather evidence as well.

Bourke Cockran Jr., a law professor and former military intelligence agent, is the son of Churchill's old Irish American mentor. Mattie McGary, Churchill's goddaughter, works for William Randolph Hearst. Attracted to each other, their tempers often clash as Cockran and Mattie follow a trail from New York to Los Angeles through Canada to discover who is funding the IRA and where the arms are assembled.

But Mattie is also keeping secrets from Cockran, who has an agenda of revenge: to kill the leader of the IRA team who is responsible for the murder of his wife in the Irish Civil War. These plans interfere with foiling the arms shipment and an IRA plot to assassinate Churchill. And time is running out . . .