Set in the 18th century, the story follows Redmond Barry, a young Irishman of modest means who becomes infatuated with his cousin. His romantic aspirations are shattered when she becomes engaged to a British officer. Driven by heartbreak and ambition, Barry challenges the officer to a duel and, believing he has killed him, flees his home to avoid arrest. He joins the British Army but soon deserts and is captured by the Prussians. After displaying cunning and bravery, he earns a position in the Prussian military and later becomes a protégé of a Prussian nobleman, leading a life of deceit and adventure across Europe.

Barry's fortunes take a dramatic turn when he seduces and marries a wealthy widow, Lady Lyndon, assuming the title of Barry Lyndon. He enters high society but faces the challenges of maintaining his newfound status. His behavior grows increasingly reckless and tyrannical as he seeks to secure his family's financial future and social standing. Meanwhile, his strained relationships with Lady Lyndon and her son from her first marriage set the stage for growing tension and inevitable downfall.