A Step from Heaven by An Na is the story of a young immigrant's life from childhood to adulthood told in snapshots. Each chapter is a small scene of Young Ju's life that helps to shape the woman she becomes. The novel begins with Young Ju as a baby playing in the ocean with her parents. Her father, Apa, drinks heavily. He alternates between abusive and neglectful. Young Ju's mother, Uhmma, dreams of the opportunities she believes her family would have in America, so she convinces Apa to write to his sister who lives in the United States. Apa's sister, Gomo, helps the family immigrate to America. Young Ju is so impressed with her parent's talk of America, Mi Gook, that she confuses it with her grandmother's descriptions of Heaven. They must travel in a plane from Korea to American, in the sky, her mother tells her. In the sky is where her grandmother has told her Heaven is located.

When Young Ju arrives in America, she finds that it is not the Heaven she expected, and decides that it is a step from Heaven. She begins school, and everything she learns she takes home to her parents. Her mother gives birth to a son after arriving in the new country, and the son becomes the center of the family. Apa loves his son, Park Joon Ho, in his own way and Young Ju is fiercely jealous. Apa lectures Joon sternly, and beats him to make him strong. Joon quickly becomes hard and withdrawn.

Young Ju develops a friendship with Amanda, a girl Apa does not like. She is too American, he says. Apa works two jobs, and Uhmma has at least three, so they do not spend much time with the children. Young Ju uses their absence as an opportunity to spend time with Amanda, but the girl and her parents never learn where Young Ju lives. Apa becomes increasingly fond of alcohol, earning himself a DUI and a pink slip from his cleaning job. He is absent more often with no explanations and has become more unpredictable. Since he is no longer busy working nights cleaning law offices, he sees Amanda and her parents drop Young Ju off at the library steps. Infuriated, Apa confronts Young Ju about her lies and mercilessly beats her. When Uhmma protests, he begins to beat her, and Young Ju calls the police.

Apa is arrested. The following morning his family waits for him to be released at the police station, but when Apa leaves the building, he ignores them. He gets into the car of another woman, and his family never sees him again.

Uhmma learns from Gomo that Apa is returning to Korea. Uhmma buys a home for her children the same year Young Ju earns a scholarship for college. Young Ju leaves for college a few months after the family moves into their new home. Young Ju makes peace with her memories of her father, and learns to appreciate the scars on her mother's hands.