A ruined count, a wife who has ceased to matter to him, a mistress who intends to be a countess, and a baron who drinks in public and misses nothing. Gaboriau was a cavalry trooper and a lawyer's clerk before he created Monsieur Lecoq and, with him, the detective novel in France; this is the second half of a story about a family taken apart methodically, and the vengeance of the title is served cold and legally.