My impression re: George C. Marshall, is that she was critical of Marshall's willingness to follow the Roosevelt path in the immediate wake of the Second World War. Only after Churchill threw down the gauntlet at Fulton was the cold war on in earnest.
She does not accuse Marshall of treason. She does accuse him of gullibility on some issues.
Coulter's central thesis remains despite the invective hurled at her: the Democratic Party was suborned by the First Chief Directorate of the NKVD. This occured during the 1930's when young radicals were brought from colleges to work in government during the New Deal. Whittaker Chambers was one of the few who turned from being a spy to being a patriot. Hiss remained in the pay of Stalin, as well as Harry Dexter White, Greenglass, the Rosenbergs and numerous others.
The Democrats as a party were not concerned about the penetration of their party and the Government. They had too much invested in Roosevelt's postwar vision of a United Nations and a grand bargain with Stalin. Again and again, they had to be dragged kicking and screaming to the realization that Stalin, Beria, and that crowd was an assemblage of butchers such as the world would not see until the rise of Mao.
Methinks that Joe McCarthy achieved far more than Conason would give him credit for, and I await some serious historical scholarship on the era. Thankfully, the one conservative who didn't overreach was Nixon, and he would survive to fight another day.
Be Seeing You,
Chris