This story is Balzac's sequel to the immensely successful Anglo-Irish gothic novel Melmoth the Wanderer (1820). In that gripping but rather tediously overwritten novel, Melmoth has signed his soul over to the devil in return for along life and superhuman power. (The story is in the mode of the Wandering Jew, the Count of St. Germain, Joseph Balsamo/Cagliostro, Faust.) Wandering the earth, he tries to persuade someone to take over the bargain so he can die in peace. In addition, the original is a strong criticism of Catholic monasticism and the Spanish Inquisition.
Balzac's version takes place nit in some Irish castle or Spanish dungeon but in the contemporary Paris of the Comédie humane, where the protagonist, Rodolphe, is the cashier at the banking house of Nucingen, a war veteran who has enormous sums passing through his hands, but who takes home a modest salary.
We soon learn that ge is keeping a mistress – as ever in Balzac a crushingly expensive proposition. As he starts to pull off a swindle at the banking house, he is approached by the all-knowing Melmoth who shows him how his theft will be discovered and how he (Rodolphe( will languish in jail, unless he takes on the curse.power of Melmoth.
Faced with a treacherous mistress and seemingly inevitable ruin, he makes the switch. Melmoth goes off to receive last rites and die in peace. Rodolphe at first enjoys the new powers, including the ability to obtain money and sex at will, and the ability to read others minds. He soon becomes satiated, bored, then desperate to pass on the curse and die himself.
We see a series of passings on of the curse, for lesser and lesser goals, until it finally just peters out. The point seems to be that the triviality of Parisian life can't sustain the cosmic melodrama of the original story.
I find the best part of the story is the description of the love affair, how the mistress comes to expect ever treater luxury and the cashier is too dazzled, too pround, and too scared, to explain that ether is a limit to how much he can spend on her. This fits in with Balzac's doctrine (all too true in his own life) that luxury is purchased at a horrible price in anxiety and toil:
sous le luxe inaperçu de la plupart des ménages parisiens, reposent d’écrasants soucis et le plus exorbitant travail.
the unnoticed luxury of most households in Paris rest upon crushing worries and the most outrageous work