A Step From Heaven is the story of a Korean-American immigrant family and how they navigate their lives in a new land.
The protagonist of the story is Young Ju; her family consists of Apa (her father), Uhmma (her mother), Halmoni (her grandmother), Harabugi (her grandfather) and eventually, Joon Ho, her little brother. At the start of the novel, we read that Harabugi has passed away, and Young Ju is about to move with her Uhmma and her Apa to a new land called Mi Gook (America). Uhmma takes Young to get her hair curled because Mi Gook girls have curly hair, and she wants her daughter to look pretty like a Mi Gook girl. Young notices that her parents are ecstatically happy to be going to Mi Gook. It seems to be a wonderful place, so wonderful in fact, that Young thinks they are going to heaven, where her Harabugi lives. Young's Uncle Tim tells Young that while Mi Gook is a great place, it is not heaven; however, he comforts her by conceding that they can look at Mi Gook as one step from heaven. Gomo offers Young Coca Cola as she says that it is a Mi Gook drink and Young should learn to like it.
In America, Apa and Uhmma try to fit into their new lives. Both have to hold down a few jobs between the two of them just to make ends meet. Uhmma is pregnant with Joon Ho and tries to convince Apa that she will take on two jobs after she gives birth so that they can have a nice house to live in. Apa will have none of it; he is convinced they should rent, and save up their money in the meantime. Apa slaps Uhmma for arguing with him; he will tolerate no questioning of his decisions. Struggling to survive in America is hard and the language barrier further frustrates Apa: he takes it out on his wife and children, forgetting that life is hard for all of his family as well. Apa abuses Joon Ho physically for disobeying him; he tells Joon that if he wants to grow up to have a strong future, he must talk and fight like a man. He must never whine and complain; Joon, however, comes to hate Apa for his controlling and abusive treatment.
Meanwhile, Young notices that her father and mother are getting along badly as time passes. Apa continues to hit Uhmma if she so much as says a word contrary to what he thinks a good Korean wife should voice. Apa starts to drink heavily, and starts missing work. He is frustrated that he cannot give Uhmma and his children everything they need in this new land; he accuses Uhmma of never being satisfied no matter how hard he tries. He tells Uhmma that she is strangling him with her expectations and hopes.
As for Young Ju, her relationship with her father deteriorates quickly; at the Immigration and Naturalization office, she has to translate for her father. Apa is embarrassed by his awkwardness in speaking and understanding English; Young is equally embarrassed that she has to translate for her father. She stoically endures abuse at her father's hands for being friends with an American girl, Amanda. Apa thinks that Young is learning bad American habits from Amanda and forbids Young from seeing Amanda. Meanwhile, Joon keeps missing school; he becomes angry and detached from his family. Young begs Joon to understand that his future depends on him attending school, but Joon dismisses her concerns.
Uhmma, Joon, and Young start attending church, but Apa is not pleased that they are doing so. To him, this is just another step away from their Korean identity. Apa feels as if he has less and less control of life as time passes. The climax of the novel occurs when Uhmma tries to defend Young while Apa is beating Young. Apa turns on Uhmma and gives her the worse beating she has endured thus far. Young calls the police; the police come and arrest Apa. However, Uhmma will not press charges on her husband. It is decided eventually that Apa will return to Korea. Uhmma asks Joon and Young whether they want to go with their father, but they decline to do so, choosing to stay with their mother instead. Uhmma tells Young that her father was not always the unhappy man they have come to know. Once, he had dreams; it was he who taught Young not to be afraid of the waves at the beach. Uhmma tells Young to take the picture of Apa and Young at the beach to college and to remember that they are a family of dreamers.
As a family, Uhmma, Joon, and Young are able to forge a hopeful future for themselves in their new home, Mi Gook.