[2] Secret City is a social history of the Jews who escaped from the Warsaw Ghetto and tried to survive, living illegally "on the Aryan side".

[3] He estimates that out of the city's population of about one million, about 70,000 to 90,000 gentile Poles were involved in helping those Jewish escapees, while between 3,000 and 4,000 Polish criminals and profiteers, known as szmalcowniks, preyed on those Jews and their helpers, blackmailing them or betraying them to the German occupiers.

While Kassow does question Paulsson's reliance on hindsight in his analysis of the decisions of Jewish leaders, he sees the book as a "masterful contribution to the history of the Holocaust".

"[10] Anita Shelton in History: Reviews of New Books concluded that "overall, Paulsson's Secret City impresses with its careful scholarship and restrained presentation of a controversial set of propositions".

[11] Jeremy D. Popkin in Judaism praises the book for being original, a rare contribution in the field of Holocaust historical studies, although he notes that Paulsson might have underestimated the importance of familial and communal ties in his analysis of why Jews did not seek refuge on the Polish side.

[13] Joanna Michlic, writing in Holocaust and Genocide Studies, was more critical, noting that while the book contains "skillful quantitative analysis and valuable observations about the phenomenon of survival itself", it "fails to address consistently certain major interpretive problems".