Helga Crane is a fictional character loosely based on Larsen's experiences in her early life. Crane is the lovely and refined mixed-race daughter of a Danish mother and a West Indian black father. Her father died soon after the she was born. Unable to feel comfortable with her European-American relatives, Crane lives in various places in the United States and visits Denmark, searching for people among whom she feels at home.
In her travels she encounters many of the communities which Larsen knew. For example, Crane teaches at Naxos, a Southern Negro boarding school (based on Tuskegee University), where she becomes dissatisfied with its philosophy. She criticizes a sermon by a white preacher, who advocates the segregation of blacks into separate schools, and says their striving for social equality would lead blacks to become avaricious. Crane quits teaching and moves to Chicago. Her white maternal uncle, now married to a bigoted woman, shuns her. Crane moves to Harlem, New York, where she finds a refined but often hypocritical black middle class obsessed with the "race problem."
Taking her uncle's legacy, Crane visits her maternal aunt in Copenhagen, where she is treated as a highly desirable racial exotic. Missing black people, she returns to New York City. Close to a mental breakdown, Crane happens onto a store-front revival and has a charismatic religious experience. After marrying the preacher who converted her, she moves with him to the rural Deep South. There she is disillusioned by the people's adherence to religion. In each of her moves, Crane fails to find fulfillment. She is looking for more than how to integrate her mixed ancestry. She expresses complex feelings about what she and her friends consider genetic differences between races.
The novel develops Crane's search for a marriage partner. As it opens, she has become engaged to marry a prominent Southern Negro man, whom she does not really love, but with whom she can gain social benefits. In Denmark she turns down the proposal of a famous white Danish artist for similar reasons, for lack of feeling. By the final chapters, Crane has married a black Southern preacher. The novel's close is deeply pessimistic. Crane had hoped to find sexual fulfillment in marriage and some success in helping the poor southern blacks she lives among, but instead she has frequent pregnancies and suffering. Disillusioned with religion, her husband, and her life, Crane fantasizes about leaving her husband, but never does.
Clare and Irene were two childhood friends, both of African and European ancestry. They lost touch when Clare's father died, and she moved in with two paternal white aunts. She started to 'pass' as a white woman and married a white man, who is a racist.
Irene lives in Harlem, where she identifies as black and commits herself to racial uplift. She marries a black doctor. The novel begins as the two childhood friends meet later in life. Events unfold as each woman is fascinated and seduced by the other's lifestyle. The novel traces a tragic path, as Irene becomes suspicious that her husband is having an affair with Clare. (The reader is never told whether her fears are justified or not, and numerous cues point in both directions). Clare's mixed race is revealed to her husband John Bellew. The novel ends with Clare's sudden death by "falling" out of a top floor window in a multi-story apartment building. The end of the novel is famous for its ambiguity, which leaves open the possibility that Irene pushed Clare out the window, Clare fell accidentally or she committed suicide.
Many see this novel as an example of the plot of the tragic mulatto, a common figure in early African-American literature after the American Civil War. It is usually a woman of mixed race who is portrayed as tragic, with difficulty marrying and finding a place to fit into society. Others suggest that the novel complicates that plot by introducing the dual figures of Irene and Clare, who in many ways mirror each other but also introduce differences. The novel also suggests erotic undertones in the two women's relationship, and a potential bisexuality in Irene's husband, as if the characters are passing in their sexual identities. Some read the novel as one of repression. Others argue that through its attention to the way "passing" unhinges ideas of race, class, and gender, the novel opens spaces for the creation of new, self-generated identities.
Since the late 20th century, Passing has received renewed attention from scholars because of its close examination of racial and sexual ambiguities and liminal spaces. It has achieved canonical status in many American universities.