Bella lives in extreme poverty in Tijuana, Mexico, with her young mother in a village of cardboard boxes. When she is five, a severe rainstorm causes the box that she and her mother are living in to slide down the hill and onto a road that leads to the border. As Bella struggles to save herself, an American family traveling to their beach house in Baja finds her and pulls her from the mud.
The family is asked by one of the village rescuers to care for Bella for a week until her mother can be found. When a well-fed, well-scrubbed Bella and the American family return to Tijuana, though, her mother has vanished. The family must make a decision whether to leave Bella at the Tijuana orphanage in hopes the mother will find her or take her illegally back to the States with them.
Ten years later Bella has become an important part of her new family and has adjusted to her middle-class life. When things at the American border become more tense and difficult, the family becomes concerned about Bella’s lack of paperwork and decides to no longer take her across the border to the beach house. When the family makes their trip to close up the beach property without Bella, she and her best friend make a dangerous decision that will impact Bella’s future and possibly separate her from her beloved adopted family.