Passing is a novel that closely examines racial identity, jealousy and human relationships. Irene and Clare are two friends of mixed race. While Irene identifies as black and is part of the community in Harlem, Clare has decided to "pass" as white and has married a racist man who doesn't know she is black. Although she's chosen to pass, Clare is also fascinated with the black community and uses Irene to become part of it. Her story has a tragic ending when her husband discovers her identity.
The story is written as a third person narrative from the perspective of Irene Redfield, a mixed-race woman who lives in the Harlem neighborhood of New York City.
Part One of the book, titled "Encounter," opens with Irene receiving a letter from Clare Kendry, causing her to recall a chance encounter she had had with her, at the roof restaurant of the Drayton Hotel in Chicago, during a brief stay in the city. The women grew up together but lost touch when Clare's white father died and she was taken to live with her two paternal white aunts. Irene learns that Clare "passes" for white, living primarily in Europe with her unsuspecting, rich, white husband and their daughter. Although Irene tries to avoid further engagement with Clare, she later visits Clare for tea along with another childhood friend, Gertrude Martin.
Toward the end of the visit, Clare's husband John (Jack) Bellew arrives. Unaware that all three women are black, Jack expresses some very racist views and makes the women uneasy. However, the women play along in an effort to maintain Clare's secret identity. Afterward, Irene and Gertrude decide that Clare's situation is too dangerous for them to continue associating with her. Irene receives a letter of apology from Clare but destroys it and goes on with her life with her husband, Brian, and her two sons.
Part Two of the book, "Re-encounter," returns to the present, with Irene having received the new letter from Clare. After Irene ignores Clare's letter, Clare visits in person so Irene reluctantly agrees to see her. When it is brought up that Irene serves on the committee for the "Negro Welfare League" (NWL) Clare invites herself to their upcoming dance despite Irene's advice against it for fear that Jack will find out. Clare attends the dance and enjoys herself without her husband finding out, which encourages her to continue spending time in Harlem. Irene and Clare resume their childhood companionship, and Clare frequently visits Irene's home.
The third and final part of the novel begins before Christmas, as Irene's relationship with her husband has become increasingly fraught. Aware of her friend's appeal, Irene becomes convinced that her husband is having an affair with Clare. During a shopping trip with her visibly black friend Felise Freeland, Irene encounters Jack, who becomes aware of her and, by extension, Clare's, racial status. Irene considers warning Clare about Jack's new-found knowledge but decides against it, worried that the pair's divorce might encourage her husband to leave her for Clare.
Later, Clare accompanies Irene and Brian to a party hosted by Felise. The gathering is interrupted by Jack, who accuses Clare of being a "damned dirty nigger!" Irene rushes to Clare, who is standing by an open window. Suddenly, Clare falls out of the window from the top floor of the building to the ground below, where she is pronounced dead by the guests who eventually gather at the site. Whether she has fallen accidentally, was pushed by either Irene or Bellew, or committed suicide, is unclear. The book ends with Irene's fragmented anguish at Clare's death.