The answers are here. This is effectively a 'For The Love Of Chéri' epilogue. Opening sixteen years after the events in Chéri, our narrator writes their memoires of what they discovered happened that night in the Bordello, and more importantly, what happened behind the scenes and incredible revelations they learn as well and who the people in control always were. The narrator fills in the blanks on immediately after the night in the Bordello, then six years later, then finally sixteen years later, until the final entry.
11 parts