On the streets of Paris lives a young street urchin named Gavroche. He is one of several hundred homeless children who roam the city, living in abandoned lots and underneath bridges. Gavroche’s parents are none other than the Thénardiers—he is the unwanted third child whom we see as an infant in Montfermeil. The Thénardiers now live in the Gorbeau House under the pseudonym Jondrette. Cast out by his parents, Gavroche fends for himself on the street, begging and picking pockets to survive. He is only eleven or twelve years old, but he does not blame his parents for their neglect, since he has no idea how parents are supposed to behave.
The novel focuses on the life of Marius Pontmercy. Marius is a young man who has grown up under the care of his ninety-year-old maternal grandfather, Monsieur Gillenormand, a staunch supporter of the monarchy. Marius’s father is Georges Pontmercy, a colonel in Napoléon’s army. Pontmercy, persecuted for his support of Napoléon and plagued by Gillenormand’s threats to disinherit Marius, eventually gives custody of Marius to his father-in-law.
Marius does not hold much affection for his father, because Gillenormand has told him that his father abandoned him. In 1827, shortly after Marius turns eighteen, Gillenormand tells him that Marius’s father is ill and orders him to visit his father. Marius rides out to Vernon, his father’s hometown, the following morning but arrives a few minutes after his father dies. Since Marius has always believed that his father did not love him, he finds it difficult to grieve. Marius discovers a note among Pontmercy’s belongings asking Marius to find a man named Thénardier, who once saved Pontmercy’s life at Waterloo. The note instructs Marius to help Thénardier in any way he can.
Back in Paris, Marius struggles to understand his father’s legacy. He wonders why his father, who supposedly did not love him, asked to see him before he died. The churchwarden, Mabeuf, tells Marius that his father came to Paris every two or three months to watch his son at Mass. This knowledge further confuses Marius. He immediately returns to Vernon to learn everything he can.
Marius devours history books and bulletins about his father’s exploits in Napoléon’s army and comes to admire the dead Pontmercy. To the chagrin of his grandfather, Marius also becomes a passionate follower of Napoléon. Gillenormand learns of Marius’s new political views, and the two get into a heated argument. Marius moves out, refusing any help or money from his family.
The different politics of the Gillenormand and Pontmercy households represent the political trends dividing France in Hugo’s time. Gillenormand, Pontmercy, and Marius each symbolize the major political trends of their respective generations. Gillenormand, the eldest of the three men, is a staunch supporter of the kings who ruled France in the centuries prior to the French Revolution of 1789. Pontmercy, on the other hand, is an ardent follower of Napoléon, who inherited the legacy of the 1789 revolution and acted as emperor of France until his defeat at Waterloo in 1815. After 1815, the royal family, the Bourbons, returned to power. To ensure that belief in the Napoléonic tradition is not passed down from father to son, Gillenormand intentionally isolates Marius from Pontmercy, raising him to support the Bourbons and oppose Napoléon. When Marius discovers that his father secretly loved him, however, he becomes more receptive to his father’s beliefs and begins to examine them without prejudice. As a result of his research, Marius radically changes his political beliefs, which ultimately creates a rift between him and his grandfather. The split between Marius and Gillenormand, along with Marius’s embrace of Napoléon, symbolizes the younger generation’s rediscovery of the Napoléonic values and the principles of democracy.