Through the years Castro would become close friends with writers like Octavio Paz, Julio Cortázar, Samuel Beckett, Kostas Papaioannou and Georges Schehadé.

In 1945 he found a job as a secretary in the Astronomy Observatorium of the city of Córdoba, where we also worked as the assistant to the musician Manuel de Falla in Alta Gracia, until his death in 1946.

That same year he travelled to the northeast of Argentina and the south of Perú to study pre-Columbian art with Gonzalo Fonseca, Julio Uruguay Alpuy and Jonio Montiel.

His work as a musician drew attention from relevant figures such as Wilhelm Furtwängler, Aaron Copland and Juan José Castro.

In the book is featured the intimate friendship of the protagonist, Horacio Oliveira, with his companion in the Serpent Club, whom he often visited in his studio in Paris.

He was also a close friend of the musician Alberto Ginastera, who made reference to Sergio de Castro and his first works in his notes on modern Argentinian music.