The Prisoner of Heaven returns to the world of The Cemetery of Forgotten Books and the Sempere & Sons bookshop, where Daniel, and his old friend FermÍn Romero de Torres, are tending shop. Daniel is now married with a son, and FermÍn is soon to follow. Both men lead relatively happy and quiet lives. Enter an enigmatic visitor--a grim old man with a piercing gaze--who inquires about FermÍn's whereabouts. When told he is not in, the old man proceeds to buy the most expensive item in the store, a first edition of The Count of Monte Cristo, adds a dedication and leaves it as a present for FermÍn. When Daniel reveals the details of this unsettling encounter to his friend, FermÍn reads the dedication, turns pale, and at Daniel's insistence, decides to open up about a past that has come back to haunt him a story that will leave Daniel questioning his very existence.