This paper explores the relationship with Freemasonry of the writer and journalist Francisco Ferrari Billoch (Manacor, Mallorca 1901-Madrid 1958). He was one of the most relevant examples of evolution, from belonging to the order, to joining the an-ti-Masonic propagandism in 20th century Spain. Despite his right-wing origins, at the beginning of the Second Spanish Republic, Ferrari experienced a brief masonic, secular and progressive period that, in 1935-36, gave way to a new turn towards the extreme right. This turned him -until the beginning of the 1940s- into one of the most famous Spanish libelists against the lodges and their supposed connection with Marxism and Judaism, publishing books such as La masoneria en accion (1941), La masoneria femenina (1942), Andanzas del bulo. Apuntes para su historia (1942) y La garra del capitalismo judio. Sus procedimientos y efectos en el momento actual (1943). However, after the approval of the Law for the Repression of Freemasonry and Com-munism (1940) he was prosecuted, convicted and imprisoned in the Burgos prison (1942-1945). Ferrari's trajectory clearly reveals the fascistization experienced in the 1930s by the traditional Spanish right. In addition, the role acquired by the fight against the lodges in the discourse of the victorious side after the Civil War. Besides, the analysis of the documentation included in the summary he was subjected to in 1942 allows progress in the knowledge of the mechanics of those procedures, showing the implacable nature, and the extreme illegality of Franco's anti-Masonic repression.