Agnostic Charles Ryder is seduced by the allure of the Flytes, a wealthy aristocratic family. Although he finds himself at odds with their strong Catholicism, his ties to the family deepen for the decades between the two world wars.
Early spring 1944. Army Captain Charles Ryder transports his company to brigade headquarters at a secret location. After an exhausting journey, they arrive at the new camp, Brideshead Castle, the site of bittersweet memories for Charles.
Charles spends time at Brideshead with Sebastian, meeting more of the Marchmains and discovering the role of religion in the family's lives. Charles accompanies Sebastian to Venice, where the Marchmain patriarch lives in voluntary exile.
Back at Oxford, Charles and Sebastian fall into a funk. The Lady enlists Charles to watch over wayward Sebastian, but Sebastian continues his drunken revelry. A crisis is narrowly averted, while Sebastian's mood continues to grow darker.
Charles tries to cover up for Sebastian's drinking, but Sebastian turns on him, accusing Charles of being a spy for his mother. Sebastian proves beyond help and leaves Oxford. Charles also leaves and chooses to study art abroad.
Charles returns from his art studies in Paris and journeys to Brideshead for the 1925 New Year's celebration. Sebastian has returned from an excursion to the Levant with Mr. Samgrass, but photographs of the holiday and comments made by the two clearly indicate Sebastian frequently went off on his own to satisfy his hedonistic needs. Sebastian agrees to participate in a fox hunt although he plans to make an early escape to a pub, so he asks Charles for money and his friend acquiesces. When Sebastian returns home heavily inebriated at the end of the day, a distressed Lady Marchmain questions Charles. Learning he financed Sebastian's drinking binge, she rebukes him for enabling him, and Charles leaves Brideshead, fully expecting never to return.
Looking for Sebastian, Rex Mottram visits Charles in Paris and tells him that The Lady is ill and the family's fortune is dwindling. Rex announces that he plans to marry Julia. Lady Marchmain agrees, provided he converts to Catholicism.
Back in England, Charles learns that Sebastian is living in Fez with a German deserter from the Foreign Legion. Because The Lady is dying, Julia calls on Charles to help Sebastian home. Charles travels to Morocco and finds Sebastian.
Now a painter, Charles gets a commission to paint the family's London house, which is being sold to pay off debts. Two years later, he meets Julia and the pair discovers they have much in common.
By the time the ship arrives in London, Charles and Julia have become lovers. At the opening of an exhibition of his work in a London gallery, Charles learns that Celia knows of his affair with Julia.
Planning to marry, Charles and Julia are happily reminiscing at Brideshead when the torment of Julia's Catholic conscience is released. Charles contemplates their lives since the golden days.
Lord Marchmain comes home to Brideshead to die. In the bleak spring of 1944, Charles relives his memories as he walks through the rooms with the HQ commandant. Alone in the chapel, he whispers a prayer.
