The Book of Unknown Americans is a poignant exploration of love, hope, and the challenges faced by immigrants. After their daughter Maribel suffers a life-altering injury, the Rivera family leaves their home in Mexico in pursuit of better opportunities and medical care in the United States. Their path intersects with the Toro family, immigrants from Panama, leading to a bittersweet connection between their children, particularly the love that blossoms between Maribel and Mayor Toro. Throughout the novel, these families navigate the complexities of their new life while the narratives of other Latin American immigrants are interwoven, providing a tapestry of experiences that shape the definition of what it means to be American.