Swann's Way tells two related stories, the first of which revolves around Marcel, a younger version of the narrator, and his experiences in, and memories of, the French town Combray. Inspired by the "gusts of memory" that rise up within him as he dips a Madeleine into hot tea, the narrator discusses his fear of going to bed at night. He is a creature of habit and dislikes waking up in the middle of the night not knowing where he is. He claims that people are defined by the objects that surround them and must piece together their identities bit by bit each time they wake up.
The young Marcel is so nervous about sleeping alone that he looks forward to his mother's goodnight kisses, but also dreads them as a sign of an impending sleepless night. One night, when Charles Swann, a friend of his grandparents, is visiting, his mother cannot come kiss him goodnight. He stays up until Swann leaves and looks so sad and pitiful that even his disciplinarian father encourages "Mamma" to spend the night in Marcel's room.
The narrator traces the roots of his inclination to become a writer back to Combray. His grandparents and friends encourage him to read and introduce him to Bergotte, who becomes his favorite author. Marcel is awestruck by the overpowering beauty of the landscape around Combray, especially the hawthorn blossoms that line the path to Swann's house. He loves to fall asleep in the shade of these blossoms and then walk around the outskirts of Combray, where he can admire the town church.
Watching the sun reflect off the roof tiles of the church steeple, Marcel decides to become a writer and describes what he sees to the best of his ability. One day, he accidentally comes across an open window at M. Vinteuil's house. A composer, Vinteuil died of a broken heart after his daughter took another woman as her lover. Marcel spies on the two lovers as they mock the memory of the recently deceased Vinteuil. On a separate walk, Marcel and his family chance across Swann's wife, Odette, and her daughter, Gilberte. Marcel instantly falls in love with Gilberte, but idealizes her to such an extent that he thinks her black eyes are really blue.
The novel now carries the reader back fifteen years to relate the second story—that of the love affair between Swann and Odette. Swann does not know that Odette has a terrible reputation and, thinking she will be harder to seduce than she really is, takes up an interest in her. He finds her only vaguely attractive, however, until one day when he realizes that she resembles Botticelli's beautiful rendering of Jethro's daughter in his painting Zipporrah. Idealizing Odette through the intermediary of the painting, Swann respects her beauty with all his heart and starts to obsess about her day and night.
Odette introduces Swann to the Verdurins and their nightly salon. At first, they love Swann's company and make him one of their "faithful" guests. One night, after failing to see Odette at the Verdurins, Swann looks for her all over Paris. When they finally run into each other, their passion ignites and they become lovers. The Verdurins constantly play Vinteuil's sonata, whose piercing violin crescendos make Swann so happy that he fixes an association in his mind between the music and his love for Odette.
Nevertheless, Odette quickly begins to tire of Swann, who in turn is hopelessly in love with her. He suspects that she is cheating on him because she is such an awful liar, but his obsession for her runs so deep that he ignores the truth about their failed romance until there is no turning back: he must suffer the tormenting pangs of unrequited love. The Verdurins grow suspicious and jealous of Swann's famous friends, including the Prince of Wales, and begin to push him out of their social circle. Odette begins to cheat on Swann with Forcheville, another of the Verdurins' guests; Swann discovers this infidelity by reading one of Odette's letters to Forcheville.
One of Swann's closest friends, Charlus, tries to turn Odette back toward Swann but ends up sending him an anonymous letter about Odette's history of infidelity. Swann finally confronts her and learns the truth about her torrid sexual escapades. Dumbfounded, Swann retreats back into the high society of aristocrats and royalty that he had enjoyed before meeting Odette. His suffering soon diminishes, and he gets used to seeing her only rarely. One day, after realizing the extent to which he had based his vision of Odette on the idealized version of a Botticelli figure, Swann exclaims disbelief at having experienced the greatest love of his life for a woman who wasn't his "type."