Carlo Ginzburg is one of the most eminent contemporary historians, a professor at UCLA, and the author of internationally translated books such as The Witches' Sabbath, The Cheese and the Worms, and The Night Battles. At the start of a new research project, he agreed to let Jean-Louis Comolli follow his progress for over a year. The idea behind the film was not to show a historian imparting his research results and detailing his work, but to track the course of his research and the various questions it gradually raised. Footage shot during appointments with the filmmaker punctuates the presentation of Ginzburg's progress and reflects the way his thinking develops. These sessions were filmed in the book-filled apartment where Ginzburg stays when in Bologna. Each session resulted in a film of about 90 minutes, allowing viewers an extraordinary insight into the advance of a research project and the emergence and construction of hypotheses from traces and documents requiring comparison and interpretation.