He reported about the state of Poland, its many competing resistance factions, and also about Germany's destruction of the Warsaw Ghetto and its operation of extermination camps on Polish soil that were murdering Jews, Poles, and others.

Reves set a number of conditions which shaped the book, from the first person, "eye-witness" narrative style, which he considered popular among the American readers, to the censorship-motivated avoidance of the controversial topic of Polish-Soviet relations (at that point, in 1944, the Soviets were one of the Allies, and the American government wanted to minimize the public confusion stemming from the fact that in 1939, the Soviets Molotov–Ribbentrop Pacthelped Germany by jointly invading and occupying Poland[5]).

[1] Because of Karski's association with the Home Army, his story and the book itself were subject to communist censorship in the People's Republic of Poland.

In effect, as noted by the historian Joanna Rzepa, the first edition "presented a relatively black-and-white picture of World War II, with Poles and Jews struggling for survival under the Nazi regime".

[10] Due to a Soviet Union propaganda campaign against Karski, some translations were cancelled or delayed (these included among others Hebrew and Arabic).

[2] That same year, Joseph S. Roucek reviewed the book for Military Affairs, concluding that it is "an extremely valuable documentary survey" of an underresearched topic, here, the operation of the underground and secret societies and movements.

[16] On the other hand, Nigel Jones, who reviewed it that year for The Telegraph, noted that "it deserves its status as a Penguin Classic, not only because it is a great historic document, but also because it’s a cracking good read: Karski’s adventures are worthy of the wildest spy thriller".

[6] Marek Kohn in his review for The Independent, also that year, wrote that "Karski provides an astonishing insight into the operation of the secret Polish state", and that his story is "deeply welcome" and "deserves not just revival but reflection".

Karski, who met a number of British and American journalists in 1943, came to the conclusion that the Western Allied public saw Poles primarily as passive victims.

The very name of the book, Story of a Secret State, refers to the Polish Secret State, a political and military entity formed by the union of resistance organizations in occupied Poland that were loyal to the Government of the Republic of Poland in exile in London, encompassed not only military resistance but also underground civilian structures, such as education, culture and social services.