LUCY is a novel or novella that concerns a year in the life of Lucy Josephine Potter, an émigré to the United States from a small island in the Caribbean. At nineteen, Lucy is to serve as an au pair in a large (unnamed) American city to Lewis and Mariah, a fairly well-to-do married couple with four little girls. Lucy is the book's main character and the events of her life in the United States and the West Indies, along with her external and internal reactions to those events, are the main subject of the book. Lucy is an extremely intelligent young woman, with a deep perceptiveness about the nature of other human beings. She easily sees through fake behavior and notices facts about others long before they realize it themselves. Lucy is also an incredibly angry person, as well as jealous, cynical, and jaded.

As Lucy is introduced, it becomes clear that something in her past in the West Indies has made her this way. In part due to her emotional constitution, Lucy is unable to form permanent or deep emotional attachments, and while she likes many of the people in her life, her connections with them never run deeply. Even her sexual encounters, despite being pleasurable, are not sources of emotional intimacy for her. Lucy's anger and jealous is bound up with an inability to love deeply, and these two features of her personality seem to derive from a relationship gone wrong with her mother, Annie Potter, back in the West Indies.

The book has five chapters, which have a stream of consciousness style. The book's events are not in chronological order and contain many flashbacks. Chapter 1, "Poor Visitor," describes Lucy's arrival in the United States and her attempts to grow accustomed to life in the United States. Lucy finds Lewis, Mariah and their children to be unbearably happy and cannot understand why anyone would be so happy. Further, Lucy cannot connect with them, in part because she cannot comprehend them. In Chapter 2, "Mariah," we learn more about Mariah, Lucy's employer and new mother figure. Mariah is a complex character, but she is in many ways Lucy's opposite. She is happy, kind, peaceful, naive, and loves with great ease. Lucy finds this fascinating.

Chapter 3, "The Tongue," introduces the reader to many characters in the book and deepens the reader's knowledge of present characters. We learn that Lewis and Dinah are having an affair. We discover that Lucy is exploring her sexuality but is unable to use to express intimacy, particularly in her relationship with Hugh. The complications her personality causes her close friendship with Peggy is also evident. In Chapter 4, "Cold Heart," we explore Lucy's life. Her relationships are starting to fall apart, and her life of the past year is waning. The climax of the book comes when she receives a letter from her mother informing her that her father has died. Lucy is forced to struggle with the fact that her mother and father never expected much of Lucy, despite how intelligent she was. This was because she was female and her society never permitted much to be expected of women. After the climax, in Chapter 5, Lucy leaves Lewis and Mariah's for her own apartment with Peggy. She gradually withdraws from all her personal relationships until she is completely alone. The book ends with Lucy expressing her deep anguish that she is unable to love.