Who is the man behind the pen name of Yvon, the author of “L'U.R.S.S. telle qu'elle est”? This paper intends to highlight this figure who is still almost unknown. Yvon, the pen name of Robert Guiheneuf, was an autodidact, who grew up in the anarchist movement. However, his commitment in the Communist party, from 1921 onwards, found its concrete expression in his journey to the “Red Russia.” He lived there for years, meeting almost all the French living in the U.S.S.R., like Pierre Pascal or Boris Souvarine. His aim was to see how the people lived their Revolution. During his ten-year stay, he belonged to several networks, like the anarchist “commune of Yalta” and the Russian Esperantists. A carpenter in France, he held white-collar jobs in several wood-processing corporations in Russia and in Siberia. That is when he had the idea of telling his story, first by sending papers to La Révolution Prolétarienne, and subsequently publishing a book. The numerous reviews of the book, published in the Russian and French newspapers, prove the impact of his testimony, with most of them praising the precision of the narrative and the wealth of evidence.