It was not long before Hede had fallen in love with Massing: "My relationship with Paul grew like something so natural and so completely uncontrollable that it is almost impossible to recall how it started.
Freed by an amnesty after five-month solitary confinement in Sachsenhausen, Massing wrote his autobiographic novel Schutzhäftling 880, published in 1935 under his pseudonym Karl Billinger, dedicated to all comrades in concentration camps.
In spite of this experience, the couple "continued to render modest assistance" to Soviet intelligence during the years of World War II.
When the FBI questioned Hede Massing about Gerhart Eisler, her first husband from 1919 to 1923, who had been an illegal immigrant and an agent for the Comintern to the U.S. in the 1930s, but was now (from 1941) a legal refugee, both began slowly to confess their Soviet work.
In August 1942, Paul Massing notified NKVD that his friend, Franz Neumann, had recently joined the Office of Strategic Services.
Massing reported to Moscow that Neumann had told him that he had produced a study of the Soviet economy for the OSS's Russian Department.