Les Misérables opens not with its hero but with a saint. Hugo devotes the first book to Bishop Myriel, called Bienvenu, a man who has given away his palace and income to the poor and who insists there are no bad men, only bad cultivators. When the ex-convict Jean Valjean, turned away from every door, is taken in by the Bishop and repays him by stealing his silver, the gendarmes drag him back. The Bishop tells them the silver was a gift, adds the two silver candlesticks, and quietly charges Valjean to use the money to become an honest man. This undeserved mercy is the hinge on which everything that follows turns.
Valjean disappears and resurfaces years later as Monsieur Madeleine, a prosperous, beloved factory owner and mayor who demands one thing of his town: be honest. Into his orbit falls Fantine, a young woman seduced and abandoned, dismissed from his factory, who sells her hair and her teeth and finally herself to support a daughter she has left with the brutal Thénardiers. Hugo presents her descent as something society does to her rather than something she chooses, and the relentless Inspector Javert hovers over both Fantine and the mayor he suspects of being a hidden convict.
Valjean's conscience forces a series of costly choices. When another man is about to be condemned in his place, he reveals himself rather than let an innocent suffer. He escapes again to keep a promise to the dying Fantine, rescuing little Cosette from the Thénardiers and raising her in hiding in Paris. The novel widens here into long meditations and panoramas (the battle of Waterloo, the Paris underworld, the convent, the sewers) so that one man's story is set inside the whole machinery of a society.
The young Cosette and a poor student, Marius, fall in love just as Paris erupts in the republican insurrection of 1832. The friends of the ABC raise a barricade in the narrow streets, and Hugo turns the doomed stand into an epic of ragged, starving men who become Titans. Javert is captured there as a spy; Valjean, given the chance to kill the man who has hunted him for decades, instead sets him free. When Marius falls wounded, Valjean carries him on his back through the filth of the sewers to safety.
Javert cannot reconcile the criminal who spared him with the law he has served as an absolute, and the collapse of his certainty destroys him. Valjean delivers Marius and unites him with Cosette, but believing his convict past would stain their happiness, he withdraws into solitude and begins to fade. Only at the end do the young people learn what he did and come to him; he dies in peace beneath the Bishop's candlesticks, his last words that it is nothing to die but dreadful not to live. The novel closes having argued, across its enormous length, that conscience and mercy can outweigh both crime and law.