Julien Sorel is just a poor carpenter's son. His love of reading has given him all kinds of grand ideas about becoming a great man. The only problem is that Julien is living in early 19th-century France following the fall of Napoleon Bonaparte. The country is basically run by an unquestioned king and a bunch of superficial elites who wouldn't know honor if it slapped them in the face.
Julien catches a break when he's hired to be a tutor for the children of the wealthy Monsieur de Rênal, mayor of Verrières. Julien has an affair with de Rênal's wife and has to leave town to go to priest's school to avoid the scandal. While at the seminary, he gets another new job as a personal secretary for the Marquis de La Mole, one of the most influential men in Paris.
Julien goes to live with the Marquis, but is quickly disillusioned by how superficial and boring life in the upper-class parts of Paris can be. No one says anything with any conviction and the world is just filled with a bunch of snarky social climbers. Julien forms a romantic relationship with the Marquis' beautiful daughter Mathilde. The problem is that both he and Mathilde only want what they can't have, and this creates a certain love-hate dance between them.
Acting on the advice of a Russian friend, Julien beats Mathilde at her own love games and secures her affection. She also reveals to him that she's pregnant with his child. The two decide to get married. Mathilde's dad is furious that Mathilde wants to marry a peasant, but he eventually agrees and gives Julien everything he'll need to live as a wealthy man.
Unfortunately, the Marquis withdraws his support for the wedding when he receives a letter from Julien's old flame, Madame de Rênal. Madame's letter says that Julien is a dastardly opportunist who only seduced Mathilde to climb the social ladder. After losing his father-in-law's trust and respect, Julien travels back to his hometown of Verrières and shoots Madame de Rênal. She lives, but he's imprisoned and sentenced to death anyway.
Julien makes sure to use his last days in the limelight to criticize France and all of its hypocrisy. He is then beheaded and everyone in France goes back to their insincere, superficial lives.