W.E.B. Griffin Zero Option

November 1943. Stalin is pressing the Allies to open a second front in Europe in order to ease the pressure on the bloody grinding war in the East. Roosevelt and Churchill agree to meet the Soviet premier in Tehran.
Wild Bill Donovan, the charismatic leader of the OSS, has intelligence that someone is planning to assassinate either or both of the Western leaders at the conference. He sends his best agent, Dick Canidy, to thwart the plan, but how can he do that when he doesn't even know if the killer is a Nazi or an Ally?