While Mathieu Sapin is writing a few pages of comics for the fortieth anniversary of the François Mitterrand's election, he turns - in order to find the small story in the big one - to the shadowy figures of the Socialist Party, first and foremost Julien Dray, the "Black Baron". Through anecdotes and unpublished testimonies of evening visitors who rubbed shoulders with the highest spheres of the State since May 10, 1981, Mathieu Sapin embarks on an investigation that will answer the major political question of the SP: "Who killed the largest party of the French left?"